Velocity WAY over book values, what causes this?

Developing a load for shooting buddy in his 243 Savage model 11BL with 22 inch, 9 1/4" twist stock barrel. He wants a hunting load so used the Hornaday 87 grain V-Max, new Winchester brass, CCI250, and 43.5 grains of IMR 4831. Various manuals put this load at around 2900 fps and it shoots a very nice .6 MOA when loaded to touching the lands. Trouble is, it's making 3250 to 3300 fps according to my Magnetospeed, and starting to show pressure signs. BTW, this gun has experienced a mild overpressure event before, blown primer, lost extractor, jammed ejector, etc. Bolt got a lot of new parts and trip to the Smith for a thorough check out.

Load development has been a problem for him and me also with this rifle. Seems the throat is very tight, one might say a bit too tight. A lot of scrubbing and cleaning of the chamber and throat, and verifying with my endoscope that it is carbon free, but still a bullet placed onto the lands shows a lot of scraping along the Ogive from the throat, and takes a fairly hard push to get there when using my Hornaday OAL gage.

An OCW load development shows rounds gradually tightening up from 3 moa to under 1 as bullet is moved closer to the lands in .005 increments once we settled on a powder charge, but at touch, the group suddenly jumps up 1 moa and tightens considerably. I suspect a jump in pressure is being seen.

What do you guys think? Is that kind of jump in apparent pressure typical when loading onto the lands, or do we have a dangerously tight throat?

Any thoughts or suggestions from the vast brain trust here would be appreciated!

Would say that you are way over pressure. When you reach reloading book max velocity, time to stop. Some chambers may be somewhat oversize and allow this but, sometimes pressure can be deceptive. Better safe than sorry.

It's at the mid to low end of the loading chart, no where near the max load for this powder and bullet. That's why the question.

It's time to forget what the book is telling you and listend to what your rifle is telling you.

Any time you load at or into the lands you will start to gain pressure and velocity.

You need to back off the powder and/back off the lands. You're approaching dangerous territory (again).

Op,

Please, please STOP!

Time to "read and heed", your load is MUCH hotter than you think. From the Hornady 7th Ed Reloading Manual, pg 239:

87 gr bullet, IMR 4831, STARTING LOAD = 40.8 grs, MAX LOAD = 43.8 grs.

This is with a STANDARD Fed 210 primer.

You are using a MAGNUM primer, and you're jamming your bullets into the lands, AND you are right up near a max charge of powder.

Please, Dear God, tell me you are not also crimping your loaded ammo.

You are playing with lightning in a bottle, and you're going to get a rifle destroyed, or worse, get people injured.

Look at the reload manual and see what they used to test. Chances are not the same barrel length or twist. If identical, Then your chrono is off.

You're load "sounded" hot to me, but I don't load that powder combo in my 87 gr 243 loads, so I grabbed my Hornady manual to be sure.

Please be careful. I would pull all those loads down and start over. And for God's sake, stop using magnum primers in that load. Especially if you're going to jam bullets into the lands.

Quote:

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Originally Posted by Texas10

1) used the Hornaday 87 grain V-Max, new Winchester brass, CCI250, and 43.5 grains of IMR 4831.
2) Various manuals put this load at around 2900 fps and it shoots a very nice .6 MOA when loaded to touching the lands. Trouble is, it's making 3250 to 3300 fps according to my Magnetospeed, and starting to show pressure signs.
3) Load development has been a problem for him and me also with this rifle. Seems the throat is very tight, one might say a bit too tight. A lot of scrubbing and cleaning of the chamber and throat, and verifying with my endoscope that it is carbon free, but still a bullet placed onto the lands shows a lot of scraping along the Ogive from the throat, and takes a fairly hard push to get there when using my Hornaday OAL gage.

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Texas10,
These things tie together and will try not to blur for the sake of clairty.
1 & 2) Don't know what books you are using(how old), but this is a classic case of misunderstanding the oft understated warnings. ALL powders come with a warning, stating to "Drop loads 10% when switching lots". If you double check the only one who lists nominal variations(Western), you will see that lot variations of 10% between powders is completely reasonable. Hodgdon's current data shows you to already be over max by charge, and matching book max velocity. So here is the why: No one lists lot numbers tested, or if they themselves tested or merely re-printed the data. All good data comes from SAAMI minimum spec universal receivers and minimum spec bore and groove barrels. You are working with a mass produced animal, which will have some amount of larger tollerances. Meaning you will bleed more gas, and have lower velocities. So as was stated, whenever you match book velocities, you beat book pressures. So compared to current Hodgy data, your lot is burning faster. The next fly in the ointment is the cartridge and powder. The 243 is imfamous for having wild unexplained pressure excursions when using slow powders. It is usually more troublesome with heavier bullets, but remains in any case. So that could be playing into this as well.
As for the Mag primer comment. Remember that magnum primers came from a request of Roy Weatherby. He himself didn't like shooting his 300 case to full load pressures. After using that case in the Rockies with substantially downloaded capacity, he found ignition issues. Many will claim that it is for ball powders, which is only sort-of half correct. It is true that ball powders will have more air gap between particles, and with a substantially reduced case fill; some very old tech ball powders could actually run-out of air production to sustain ignition if the flame front wasn't aggressive enough. Speer was a leader in that "change", but that didn't happen until 1989-ish. Aluminum was one of the additives to have more "Sparklers" if you like, to aggressively ignite things. However total output isn't substantially increased. No doubt, they are different, but not massively so. All things depend of course, but in my 308 & Creedmoor, swapping magnum primers with standard produced no significant differences detected by the Pressure Trace. Not to say that ALL primers are the same, nor that all powders and loads will be the same. But don't take a sky is falling claim as gospel. Simply remember that when you switch any component, things change.
3) The throat is up to you to determine. I honestly haven't used a books OAL in so long, I can't tell you what any of my rifles are. I always load them for themselves. So take an un-primed, sized case and just barely seat a bullet. Then drop it in the chamber and slam the bolt home. Carefully extract it and measure, this tells you your jam length. Back-off as appropriate for your own desire, or mag length. Personally I like 1/32" of jump, unless a mag length issue arises. While velocity suffers when seated more deeply, I personally think that far too much is made of the importance of jump length for accuracy. There are shooters out there that perhaps it matters for, but not the masses. In my rifles even when chasing my mile targets, ALL bullets get seated to the 32nd jump. Any lack of accuracy, assuming proper powder charge work was done, isn't from bullet jump; it's me missing the wind calls.

Cheers

darkker,

1. The OP has already had one "overpressure event" with this rifle.

2. The OP thought he was "no where near" max with his load.

3. The OP substituted magnum primers for standard primers while jamming bullets into the lands with a max powder charge.

The sky is indeed falling.

Back it off a couple grains and try it again with the same seating depth.

I've got a "fast" .308 from PacNor. I too have chased bolt parts out of this rifle. Wakes a guy right up. Sure is a good shooter!

I agree that he's over pressure, I further explained how to understand that. Further I was merely clarifying the history of mag primers, and potential (not absolute) differences. Taken only at face value, your statement would imply anyone jamming bullets couldn't use a mag primer; or that it positively does raise pressures, which isn't the case absolutely.
So, to repeat what i said, when things are different, they are different.

Explaining why he is off is helpful to the cause of him wanting to know what's going on. Telling him he's going to blow himself up especially if using a mag primer, isn't, even if a correct warning of his current pressure situation.
The sky isn't falling, the clouds are merely at a lower altitude.

Thanks, Darkker. Believe it or not, I do pay attention to what's printed here, especially those i know and are quite knowledgable and helpful. The OP has not had an overpressure event....EVER! But the subject gun has experienced such and event, and that is why I am helping with the load development. Trying to keep my friend healthy and alive, but there's something strange with this barrel, and THAT is what I am trying to sort out.

The Hornaday max load is at 2900 fps. I have checked LEE, Nosler, and Sierra, in addition to Hogdon website. All current additions, and this is the lightest load listed.

Loads were started low, and worked up. Magnum primers were added when we saw large elevation changes in all loads. My take was ignition issues. That change by itself made the desired difference in group shapes, from minimum load to near max all groups formed circles instead of vertical lines.

Nothing was out of the ordinary, no signs of pressure (sorry Darkker, no strain gages on this action) until touch. Then BIG boost in velocity, with only the beginnings of primer cratering.

Nowhere have I read that switching to a magnum primer will result in a 400 fps gain! I suspect that if that were typical, all the long range guys would shoot nothing but magnum primers. I am certainly no expert, but I don't think that's the case.

So what I am asking here, and BTW I am reading about a similar issue regarding a Stealth that might have a short chamber, is this: Would a tight throat cause a significant increase in muzzle velocity such as we are seeing? I know it can raise starting pressures, but 400 FPS?

IF SO....what is the correct course of action? Replace the barrel? Have it re-throated? This gun has been a problem child since new, 25 some years ago and I'd like to identify the problem and fix it, if possible.

Thanks for all your help, guys. Looking forward to your responses

Tex,

I'm glad you clarified the "overpressure event" in your follow up. What concerned me the most in your original post was your assertion (an incorrect one) that your listed load was no where near a max load. I don't know where that info came from, but if you're extrapolating data from other sources, this is quite a bit off from the Hornady manual. 43.8 grs is listed as a max load, and you're 0.3 grs under that, and thinking that you're at a low to mid scale load (your follow up post). This is a huge red flag that something is quite seriously wrong, and a FULL STOP is in order.

As far as velocities go, there are many possibilities why your velocity is "off" from the book. Firstly, the Hornady manual lists that max load as having a 3100 fps muzzle velocity. These test loads in the manual were fired from a Winchester M70 with a 24" bbl. First, there are differences in rifles, chambers, barrel lengths, and even how "fast" a barrel is. Second, there are differences in measuring equipment, aka chronographs. If you took 3 or 4 different rifles, all chambered in the same cartridge, with the same barrel lengths, you would see differences in muzzle velocity when shooting the exact same load over the same test chronograph. Similarly, if you took one rifle, with identical loads, and fired them over multiple chronographs, brands, styles, etc, you will also see a difference in measured muzzle velocity. I have seen rifles that were a couple hundred fps off from each other when shooting the same load. I have also seen chronographs that were several hundred fps different from each other when clocking the exact same rifle and load. That is just The Way of Things.

Darkker,

Reading into my words that the use of magnum primers will bring the end of the world is a huge disservice. That is not what I said, nor what I meant. You are correct that each rifle is it's own individual animal, and needs to be treated as such. Just because you (or I) have a rifle that switching to magnum primers in makes "little difference" is irrelevant. Some barrels, chambers, throats will take the switch with no problem, and some can be a big problem. But for a loader (any loader) to take a max load, with the bullet jammed into the lands, and proceed to use a magnum primer where the load recipe called for a standard primer, should only be done with caution, and only done while slowly working the load up from scratch. Doing so invites an initial pressure spike, as the increased ignition wave due to the bullet not moving sooner in the wave cycle. It can be done, but must be done carefully, and with purpose. Not just swapped in to see what happens (not saying that is the case with the OP). But switching to a magnum primer in a max load, where the bullet is already jammed into the rifling gives the chamber (in this case actually it's the cartridge case that's the "chamber") no where to go. The bullet will sit motionless for a longer period of time, until pressure builds up behind it enough to force it to move down the rifling. Where as if you are jumping bullets, the bullet starts moving almost immediately, as soon as pressure builds enough to overcome the neck tension on the bullet. So the initial ramp up in the pressure wave changes when you jam bullets. The initial pressure wave also changes when you use a magnum primer. More of the powder charge is ignited in the initial instant of ignition, so the pressure wave starts off sharper. When you stack those two occurrences, jammed bullets, and magnum primers, you can have an initial pressure spike in some barrels/chambers that you will not see in others.

So when a loader/shooter is having issues with pressure coming on "early", or velocity that seems too high, AND he is jamming bullets with magnum primers, then caution and load reevaluation is in order. But when a loader/shooter states he is shooting a load that is no where near max, but in fact, he is right at book maximum for that load, then EXTREME caution is in order, and a full stop is necessary to evaluate what the heck is going on.

Tex,

Look man, I'm not trying to beat you up here, I'm just trying to keep you safe.

As far as your barrel goes, I don't really see anything that makes me think you should swap the barrel. Maybe get it bore scoped if you want. Have you tried lapping the barrel? Maybe try a full clean to get it down to bare steel and start over with break in (either a foam cleaner multiple times, or a plug in the chamber and stand the rifle up and literally fill it with bore cleaner like Butch's Bore Shine), and let it stand there and soak for a couple days.

Purely as a side note, a tale of 2 rifles,

My brother has an old flat back Savage chambered in 30-06. He's had that gun probably 30 years. He hardly ever shot it, or went hunting with me, just wasn't really his "thing". One day he asked me to load some ammo for him for this rifle. Upon load development, not only does his rifle HATE every load that my Win 70 30-06 LOVES, but I found his rifle chamber was throated a full tenth of an inch shorter than my Win. That is not a typo, it really is 0.100" shorter throated than my Win. He had always complained about hard chambering in the factory ammo he bought for it, but he shot it so infrequently that a single 20 round box lasted him for many years. It wasn't until I "discovered" his short chamber, and developed a load specifically for his rifle, that he could chamber live ammo easily. I'm not sure what his chamber pressure was with that factory ammo he was jamming into that gun, but he did tell me that my handloads "kicked less" than the factory loads he had been using.

Point of all this? Maybe just that some rifles can vary wildly from each other. The safe loads that I shoot from my Win will not even chamber is his rifle.

Whatever the rifle is telling you is what matters. Regardless of what the manuals claim.

I've worked up a few loads in the same rifle with 87gr vmax and never reached pressure signs all the way up to 3,250 fps.

Keep that load around 3,200 fps max and you'll be safe.

A good gunsmith should be able to re-throat the barrel with a throater for very little money. You can purchase a throater for around $125 form PTG and re-throat it yourself. No need for a lathe either.

I gain about 50 fps when slightly going into the rifling (but not jamming). Once the projectile gets jammed into the rifling (as in the bullet is stuck and can't extract a live round) the pressure goes up drastically.

Ok, since the conversation seems to focus on the load, I'll share the result of my research when starting out on this load.

First of all, i screwed the pooch in my first post when I wrote 2900 fps. That's a starting load, not the max. Brain does funny things sometimes.

These are all based upon using IMR 4831 and 87 grain V-Max and use current publications.

Hornaday manual (groups 85 and 87 grain bullets together) lists 43.8 grains @ 3100 fps. Their info is derived from actual tests using Rem 700, 24" bbl
Lee manual (85 grain) lists 48.5 grains @ 3183 fps. Their info comes from published data, not actual tests.
Hogdon website (90 grain) lists 43.9 grains @ 3050 fps. Source unknown, probably published data.
Sierra Manual (85 grain) lists 44.5 grain @ 3000 fps as tested in Rem 700, 24" bbl.
Nosler manual (85/90 grain) lists 44.5 grains @ 3240 fps and this is their accuracy load, tested in 24" lija bbl, and Rem 9 1/2 primer.

So based upon all this information, I felt that a 43.5 grain load should be producing about 2900 to 2950 out of a 22 inch bbl (adjusting for 25 fps loss per inch of bbl.)

So, based upon all this load experience, it looks to me like we're making awfully fast headway for the load we're using, and hence my question. What's causing it?

I really don't think we're about to produce a mushroom cloud with this load, but I am curious about the greatly increased velocity. My magneto speed has been right on the money when testing factory loads with published velocities, so I am confident about its numbers.

If i back off the throat just a couple of thou, groups start to go wild.

BTW: Just before Christmas my son took his first deer ( a beautiful buck) at 220 yds with a heart shot using this gun/load. It was fortunate to have the accuracy for that shot. Deer took two steps and collapsed.

Quote:

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Originally Posted by Zero333

Whatever the rifle is telling you is what matters. Regardless of what the manuals claim.

I've worked up a few loads in the same rifle with 87gr vmax and never reached pressure signs all the way up to 3,250 fps.

Keep that load around 3,200 fps max and you'll be safe.


A good gunsmith should be able to re-throat the barrel with a throater for very little money. You can purchase a throater for around $125 form PTG and re-throat it yourself. No need for a lathe either.

I gain about 50 fps when slightly going into the rifling (but not jamming). Once the projectile gets jammed into the rifling (as in the bullet is stuck and can't extract a live round) the pressure goes up drastically.

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Thanks, Zero. That's some very useful information based upon actual experience.

No, I am not jamming the bullet. Closest we tested was touching, but again, finding the lands is difficult in this particular gun what with it's tight throat. I using the Hornaday OAL gage with modified cartridge, I can push the bullet past the throat to touch the lands, but the chamber/throat has to be free of carbon. So I cleaned very thoroughly before starting to set up this load.

To re-iterate. This gun has been difficult to load for since new, and I am looking for a good course of action to fix it. Don't want to sell a dangerous problem child to some poor un-suspecting soul. If it has a too tight throat, and that is the thrust of my query, reaming or replacing it seems to be the thing to do.

Quote:

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Originally Posted by gbflyer

Back it off a couple grains and try it again with the same seating depth.

I've got a "fast" .308 from PacNor. I too have chased bolt parts out of this rifle. Wakes a guy right up. Sure is a good shooter!

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Thanks, GB flyer (is that a Gee Bee, if so, you've got some really BIG ones:cool:), glad to read you weren't hurt while disassembling your gun while using kenetics.

My plan was to do just that, now that we've identified what jump to go with. But the larger issue is how safe the gun is. Is it defective, or within limits?

Well I guess I want to be clear on your terms, then reiterate my powder point.
You keep saying "tight throat". What that says to me is diameter. If you had a tight throat and large brass you could feel the interference/see it. If you actually mean short, then you should know that from a dummy cartridge and simply seat for the rifle, not book OAL.

Either way, short or tight, that should have been caught/noticed already in basic reloading, yes?

Take it back to powder and the warning people ignore/don't understand:
Powder can vary from lot to lot, by 10%. Say that out loud 5 times. Extruded powder has burning rates controlled by geometry mostly, coatings for temp stabilized. So if you load by weight, you ignore burning rate, which (say it with me) can vary by 10%.

Simply extrapolating what you want a speed to be, ignores all warnings about powder. No manual lists when, or by whom anything was tested. Was it calculated? Was it when that IMR plant was original, or now that it was gutted and rebuilt completely by GD? Test for what you have, not what the books prove can vary by 10%. :D

When I started pressure tracing the Creedmoor, Superformance loaded "slightly over mid-range" produced beenobviously well under start. Did I have a bad barrel? No, I had a very slow lot of powder. Well you have a faster lot. And remember that powder doesn't always just play nice, which is why a small increase/change can spike things dramatically.

Slowpoke,
Claim a disservice for repeating and unexplained caution you gave, all you want. I was explaining to the man, you were bemoaning him. I corrected your info, and you took offense. Suddenly you have time to explain how things work?
If you stick around a while you'll see that I regularly post actual Pressure Traced data. Meaning I can see exactly what is happening in my rifle.
Details are important.

If you jam bullets into the lands, do pressures always spike? Are you sure? Have you played with some of General Dynamics progressive burning powders?

http://i78.photobucket.com/albums/j8...ps0ktikfds.png
http://i78.photobucket.com/albums/j8...ps0aeacd6x.png

Quote:

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Originally Posted by Texas10

Thanks, GB flyer (is that a Gee Bee, if so, you've got some really BIG ones:cool:), glad to read you weren't hurt while disassembling your gun while using kenetics.

My plan was to do just that, now that we've identified what jump to go with. But the larger issue is how safe the gun is. Is it defective, or within limits?

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Hahaha...no...couldn't even buy a tire for one.

One thing I learned over the years, and the hard way (not too bright), is that a 87gr. bullet from Hornady is not a 85gr bullet from Sierra or a 90gr bullet from someone else. I don't know if it's bearing surface, diameter, or a combination of other bullet black magic but using numbers from one to the other is to be taken only as a very rough starting point. Looks like you figured that out much faster than I did. [emoji1]

Totally agree on lot to lot variations in powder. Most of my stuff is old including the books.

I sure wouldn't give up on the barrel if you're on to a combination that works. Nothing wrong with a 1" gun in my opinion. You might play around with different bullet weights/styles and whittle it down further yet!

Darkker, perhaps my ignorance is showing, so let me try to clear up what I mean by "throat". It is my understanding that the throat, also called the leade, is the tapered portion of the barrel forward of the chamber and before the rifling starts. When a round is chambered, this is the area the Ogive of the bullet sits if it is short of the lands. So, to clarify, I am getting scraping along the ogive of the bullet as it is pushed forward by my OAL gage while attempting to contact the lands. The bullet comes to an abrupt stop at the lands, and requires a light tap from a cleaning rod to extract. I do have a bore scope camera I use to inspect this area, and am fairly confident I am correctly describing what is going on. But since there is no way to actually see what is happening while using the OAL tool, I am to a certain extent, guessing.

Anyway, as always you offer some sage advice about powder lots and book values. I know I can simply back off the charge and give up a little group size to jump, but the larger issue here is safety of this particular gun.

I've made an appointment with a good 'smith to look at it and maybe re-cut the throat, perhaps make it a bit deeper too.

From everybody, I'd like to say that all the responses have been very useful, and I appreciate all the input from you guys. Always a pleasure to read what you have to say, and I take all of it very seriously.

Again, thank you for all the advise, and for being so quick to respond.

Quote:

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Originally Posted by darkker

Slowpoke,
Claim a disservice for repeating and unexplained caution you gave, all you want. I was explaining to the man, you were bemoaning him. I corrected your info, and you took offense. Suddenly you have time to explain how things work?
If you stick around a while you'll see that I regularly post actual Pressure Traced data. Meaning I can see exactly what is happening in my rifle.
Details are important.

If you jam bullets into the lands, do pressures always spike? Are you sure? Have you played with some of General Dynamics progressive burning powders?

http://i78.photobucket.com/albums/j8...ps0ktikfds.png
http://i78.photobucket.com/albums/j8...ps0aeacd6x.png

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Darkker,

I am seriously trying to figure out what your deal is? Seriously? You have formulated some kind of personal vendetta against me and what I posted? You say I "bemoaned him"...? Are you a child? Are you incapable of reading and understanding the written word? You think I said anything to him that was 100% wrong? At the start, I wasn't sure how much reloading experience/knowledge he had, and was not wanting to play CAPTAIN OBVIOUS with him on some rather basic details that frankly any experienced reloader should have. So, after seeing a few more of his replies, I determined that it may be a good idea to back fill in a bit more information if it would help him. So I "took the time" to explain things in more detail. You're saying my information is incorrect? In all cases?

You think it was no big deal at all that the OP THOUGHT he had a low to mid range load, that actually turned out to be a max load? I want to see you type those words, "No, it was no big deal..." You think I was wrong in cautioning him to stop what he was doing and reevaluate what he was doing? Really? That is somehow "bemoaning him"?

Pressure trace equipment. Yup, neat toy. How are you on actually evaluating the trace waves that you're looking at? Do you happen to notice, that on the 2 separate load trace charts you posted, that the one with the "jammed" bullet (your title of the chart), has a steeper pressure curve wave form (I'm speaking of the initial ramp up in the wave form now), than the load that is not jammed? You do see that, don't you? Now do the same pressure trace run, with that exact same load, only swap out standard primers to magnum primers (your data doesn't list what primer was used, so?). What do you think the resultant pressure wave will do? Stay the same? Ramp up faster? Ramp up slower?

You think I'm wrong that jamming bullets and then swapping to magnum primers will not change the pressure curve, and specifically rate of rise of the pressure wave?

And strain gauges can only measure strain on a receiver (in this case of application-they have other non-firearm related uses as well). It doesn't have any way to actually measure the pressure in a chamber. In order for a strain gauge to have any relevance, it has to be compared to a known reference load. You can get an approximation based on that reference load, that you can then extrapolate a reasonable idea of real time pressure occurring in a chamber. But the only way to gain actual pressure data is with a universal receiver with a pressure port, or to permanently modify a receiver with the same. And strain gauge data drawn from one individual rifle is only relevant to that particular rifle. So while YOUR specific rifle shows one rate of rise change by jamming bullets, are you then 100% certain and going on record as saying that ALL rifles will show the same rate of rise change by jamming bullets in their loads (in an entirely different chambering and components used)?


"...if I stick around..."

I can't wait for your next installment.

I think your diagnosis of a tight freebore/throat is the most likely cause of the erratic accuracy when "supposedly" jumping and the excessive speed.

A worn out reamer would surely cause a tight throat.

Texas my 2 cents is this I've learned that a large rifle Magnum primer is used when (1) the temperature outside is around freezing's or lower. (2) When using a large amount of very slow burning powders or in a large case, with heavy bullets. For example a 7MM Remington Magnum with a 175 Gr bullet and a powder like RE-22 out West on a Elk hunt. My recommendation is use a standard large rifle primer set the OAL @2.640 and start with 40.8 grains of IMR-4831 per the Hornady loading data and going up in .5 increments of powder.

Exactly how we started out. Min to max, eliminated the max right away, and started working on seat depth. Got the groups down to sub moa and we're planning on adjusting load by tenths. All stop now and considering options.

Quote:

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Originally Posted by Zero333

I think your diagnosis of a tight freebore/throat is the most likely cause of the erratic accuracy when "supposedly" jumping and the excessive speed.

A worn out reamer would surely cause a tight throat.

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I think you've nailed it!

I won't try to delve into the details, but when a chrono graph shows a sudden increase in speed for a given load, its gone over pressure.

So, if you want this to be relevant, you start low and work up and watch the speed.

Just targeting for a speed is totally the wrong approach, and shooting for a velocity is not the way to do it.

You take what the world gives you. If you want max velocity, you have to fine out what that is for YOUR GUN.

Not reading what load development process is or understanding it is a serious mistake.

Start off at least 10% below max, or start at the low end of listed and work up and take data.

And when its been pushed to the upper edge, then indeed a magnum primer can push you over as it can be good for upwards of 2 or 3 grains more powder.

There is a lot of variation in that due to powder speed, cartridge, gun etc.

Again the point is, start low, work up and monitor ALL the indicators going up.

There will be another one or two accuracy nodes below what you are at, take what the setup give you, not what you want.

I would like to have a million in savings, I sure don't have that. I have to live with that. If I live like I have a million there is going to be a sudden screeching stop to my world.

Thanks, RC, that's some good advise.

There's nothing less impressive than a fast miss, so I don't load for speed. I don't compete at long range, and i don't see any point in pushing my equipment to the breaking point. Typically I look for a node in the mid range as I find they usually shoot better. Sometimes a minimum load shoots the best groups and since I am mostly shooting paper at 300 yds and under, that's just fine. Uses less powder anyway so it costs less. I like that!

And I don't use my chrono for as a load development tool. If the bullets all go to point of aim and make small groups, that's all I care about. And unless I am working towards the higher end of velocity levels for hunting applications, as this load was being developed for, I am not so much concerned about absolute speed as I am SD and ES as that tells me something about ignition consistency, but so will vertical dispersion in the groups, and why I made the switch to a magnum primer. And yes, we reworked the load starting at min but dropped the previous max (44.5) by a grain.

If you'll go back and read post #19 you'll see that see that the Lee manual lists a bit over 48 grains as a max load, and several others in 44+, and we were only beginning to see a flattening of the primers and a small bit of cratering at 44.5 grains. With that i mind, and the load shooting sub MOA, it was only then that i put the chrono in use to make a drop chart and found the velocity to be rather high, which begged the question of why so fast? is it the powder? Barrel? Bullet? Bad chromo? Maybe there really was no issue, hard to tell.

To tell the truth, I only put 3 across the magneto speed. Not much of a test, but enough to tell us we were making unusually fast headway IF published loading charts are to be believed.

So you see, RC, I am not being hap-hazard or reckless, and I am pretty sure I'm not about to produce a mushroom cloud on the firing line. I do this as a hobby, not as a professional competitor. I've competed all my life and to be frank, I am quite tired of it. Tired of the egos, tired of the back stabbing, tired of the maliciousness and well, you get the point.

So I think this thread has reached it's conclusion. Most of the responses have been off course of the original question which was a mechanical fit nature, and although there is a lot of good information, I've come to the conclusion that the barrel needs to be re-throated and thats where we're going next.

My thanks to all for your fabulous ideas and input. You're a great group of friends ( I count you all as friends) with a wonderful amount of experience to share. I know I appreciate that tremendously , and I hope others will appreciate my experience and successes as well.

I have read this thread completely, and if I missed it I am sorry, but nowhere did I see brass mentioned.

For the 243 BRANDS of brass is important, and LENGTH. Make sure all brass is trimmed to specified recommended length. The 243 will really stretch brass and is reloading a lot for it and not paying attention you CAN end up with issues similar to what you are describing. Also, my early days of loading my 243 ammo, I used 308 brass and necked it down. Most of the time, it was zero issues but on occasion, the neck would come out too thick and cause a tight chamber issue.

In those days I had no idea what a neck turner was so I tossed the brass.

Check your brass for same brands, and length, in addition to the recommendations the others have given.

I just remembered this was for a friend, but please pass on this info to him.

You bring up a very good point, Handi, in fact, it was a THE point in the load development. You've read the entire thread so you know I was taking over load development on this particular rifle where mixed brass, poor headspace control and trimming issues were abundant. So I bought 100 pieces of new Winchester brass, of the same lot. I used a better (RCBS) FL die, tweaking it to only bump the shoulder as necessary to chamber, and of course trimmed to length. Neck tension=.002 as measured before and after seating the bullet. Runout down to .002 max. Neck wall thickness .015 to .016 for the most part. Plenty of chamber clearance as noted by shot brass.

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My thanks to all for your fabulous ideas and input. You're a great group of friends ( I count you all as friends) with a wonderful amount of experience to share. I know I appreciate that tremendously , and I hope others will appreciate my experience and successes as well.

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Well said and we and good balanced take.

If there is a residual truth it is that the gun was telling you things and while you did drop back a few tenths from Hornady, you ignored Hornaday data and then justified it by using other data.

My Horndady book shows 43.8 as the maxium load.

That is a very narrow range powder, while that is sort of ok, again with a known problem gun, short throat I would drop it down to the very lowest I could find. That's a clear indicator (narrow powder range) that there is not a lot of latitude for powder variation, primer deviation and or barrel status.

You also have a magnum primer in the mix when the load is close to maximum and into the lands.

The characteristic of an overload is a more than normal velocity increase per a powder increment. The term is exponential, aka logarithmic. Say the books says 1/10 of a grain increase velocity by 50 fps per each added 1/10 grain, you put it into the lands and a magnum primer and it then increases by 300 fps. Your gun is screaming at you there is an issue.


Erratic ignition is also an indicator of too much powder for the load and in this case, caused by not enough distance to the lands before the pressure spikes.

You are close to or into the lands.

All those are red alert warning signs for a gun that has shown pressure signs let alone starting a load development. Ignoring what the Chrony is telling you is a mistake as its another tool in the set.

I have done the same at times (started at mid levels though not anymore) with a a new powder and a gun that had not shown any stress indications with higher level loads and plenty of deep throating.

Even with a short throat, loaded off the lands at no less than .015, it should not show any signs pressure with a much lowered load.

I would be more interested in going to the minimum loads, non magnum primer (looking at more than one re-load book) and specific bullet mfg recommended (which you have but not sure you read it?) and then see what happens.

Hornady shows 3100 FPS for a load 3/10 lower.

While others publish other results you have a bullet mfg that has published specific results and that is where I really draw a line (for myself and recommended to others)

At the maximum end of the spectrum, you go with the bullet MFG data.

Lower end you can debate via manuals but not the upper end to start with.

You may wind up past there at some point but you are likely not to as well.

Look at the lowest loads, come up with an average and if lower than Horandy go there, then try a few rounds.

A short throat is not a problem, it gives you more barrel to use (competitors do it often and after market barrel makers offers them ).

I don't see this as a barrel problem, I see it as an ignoring good load development that bit you as all the right moves for general as well as this specific gun were averaged out to justify an ill advised load.

Start at the very low end, your pressure signs will go away and then work up slowly to higher numbers but as you know that 43.5 is too much, keep off that by at least 2 grains.

You may just have the wrong powder for that gun. H4895 is more suitable.

On a couple occasions I have loaded a string and then re-did the upper ones as they were staring to get me a sticky bolt.

Been reading the thread as it developed, and as I am a reloader with less experience than the OP, learning stuff. I like the idea of taking the rifle to an experienced smith to have him check chamber dimensions. If it is out of spec, you'll have your answer right there. Good luck and let us know how it turns out.

If that is indeed the issue it should have been done long ago.

In this case its a quick easy and safe check to reduce the load, make sure its off the lands and drop the magnum primer.

He is pushing published data. Yes you cross check data in load development, but you use the most conservative not the most aggressive and he has a proven problem barrel.

His load he is in or engaged close to the lands, he is at the upper end of that bullet mfg, he is using a magnum primer in a powder that does not require it nor was the load developed with one.

The good news is he is honest with his figures and we can assess it.

I keep getting the sense he does not believe how load development should be done.

Conservative is not looking at the maximum load you can find for all 87 grain bullets and then using the lowest of those.

Its going with the very lowest load on the charts.

I don't understand where the claim of a tight throat comes from?

You stated that you trimmed the brass, so that was eventually covered in this thread, check it again to be sure. measure the OD neck on fully prepped brass, loaded brass (which you have), and fired brass (which you have not stated?). If you have a couple thou expansion after firing - then your throat should not be undersized. The brass neck thickness you listed is on the high end - and it's possible you have neck thickening - which may also be evident if your necks on fired brass are not larger in ever so slight measurement terms >@.002.

Other concern I have - many decades ago when first starting to hand load the base instruction was to never seat bullets to the lands due to pressure spikes. 40 years later it seems seating to the lands is just a standard practice in load development. Here's the deal - you friend is going to use these loads for hunting - which means he will often need to take a loaded round out of the chamber - so seating into the lands is pointless, other than to identify/verify where they are. Back off the lands to find your best grouping - because no good group into the lands is going to be effective for your friends intended usage.

Other concern - in determining max powder charge to work with with every specific rifle/barrel, adjustments in seating depth should then be moved farther away from the lands, not closer to the lands. Getting closer to or into the lands builds pressure. If seems you had a load, which you thought was not max if I understand your post correctly, and found signs of over pressure when moving the bullet into the lands. It seems well covered in this thread that what you thought to be under max load, proved to resemble a max or over max load once moved into the lands.

The hard chambering part would tempt me to get a body die (@$25), take comparator measurements of the brass, and move the brass back a couple thousandths at a time to see if prepped but unloaded brass chambers without resistance. Hard chambering brass is typically a function of where the shoulder is - not the neck. But you won't know until you move the shoulder back.

As far as primer selection question you asked - I've not seen a big spike in chronographed speed with Magnum primers when using extruded powders like the 4831 you are using. I have seen a 200 fps difference in chronographed speed when moving from a large rifle primer to a large rifle magnum primer with a ball powder, specifically H380. In that case - my velocity was running below book values by 200 fps when using a LR primer, I dropped charge, switched to a LRM primer, and with the LRM primer in a 22-250 with H380 - my handloads were right along side with the book values, and pressure signs were less. Point is - using velocity as a pressure sign is "just one consideration". I was 200 fps under book values, starting to see pressure indications of max pressure, switched to a LRM primer and built up the next load - which had no pressure signs but matched book velocities. Who woulda thunk... My H380 was a very old can of powder (50-60 year old powder), when/if I load more with a new can of H380 powder/different lot I have it noted to drop charge weight and build up/verify load recipe again. So I've seen primer selection have a big velocity difference with a ball powder, but I have not seen the same with an extruded. It can happen though I'm sure.

Given all you have done so far, the next things I would so:

• drop powder charge .5 gr
• get a body die and chamber prepped brass to see if that solves the hard chambering issue.
• Turn your necks to uniform thickness (sorry, Winchester brass is not impressive in this area in my experience)
• Seat bullets to vary bullet jump with the longest seating .005 off the lands. Your friend has no use for bullets seated into the lands.
• Shoot for an accuracy node.

If you don't find an accurate node with that recipe - change a component, drop charge weight, and build up again. Possibly a LR primer, possibly a different powder. I honestly don't have any issue with a LRM primer in a 243 - but I've never worked up an 87 grain bullet in a 243/6mm. For my use I've only been interested in 100-105 gr bullets in 6mm and my best loads all use CCI 250 LRM primers.