Determining Maximum Powder Charge

[nubrun]

Hi gentlemen,

When working up your loads when do you typically call a given charge your maximum charge? When:

1. Sticky bolt lift
2. Ejector marks begin to show
3. Cratered or flattened primers
4. Other

Or is it a combination of all 3? The reason I ask is because I am working up a load for my 6.5x47 Lapua using Varget, CCI 450 primers and 130 gn Berger VLD's, and around 37 grains the bolt begins to get a little harder to lift, but I see no other signs. I tested all the way to 37.7 grains and still have no flattened primers or ejector marks, but the bolt is still a little tough to lift, although I don't need to karate chop it by any means. I want to squeeze everything I can out of the round, but want to do it safely of course.

Any feedback is appreciated.

Nick

[davemuzz]

Flatten primers can or cannot be a clue. That's a tough call if you rely only upon that sign....and I do not rely only on that. But, if I'm getting a consistent sticky bolt lift, the that is (for me) a for sure sign that I've reached a tad above the max. I will back the load off just a bit until I get no more sticky bolt, and if I'm getting excellent accuracy, then I'm done.

If I'm not happy with the accuracy then I'm off looking for another powder choice, or another bullet choice, or both.

FWIW

Dave

PS...This is assuming all of my brass prep is done in a consistent manner.

[FUBAR]

Using the best data I can research for that load is my first step, if I'm way above known max, even without bolt lift etc, I will stop....

Otherwise I use bolt lift the most, because I may be using brass that I have already marked up--I keep working/using brass until it fails in some way....

[scope eye]

Flat primmers usually comes first, then followed by sticky bolt in most cases anyway, you can reduce PSI by shorting your COAL, if I make batch and find they are to hot instead of pulling them apart, I just push the bullet in to the case another 50 thou that always does the trick.

Dean

[Blue Avenger]

Read the book, It lists max! You were over before the signs showed! If you insist on going into that territory.. watch the primers, ejector flow marks, measure just above the web and see if you have fast growth.

[nubrun]

Flat primmers usually comes first, then followed by sticky bolt in most cases anyway, you can reduce PSI by shorting your COAL, if I make batch and find they are to hot instead of pulling them apart, I just push the bullet in to the case another 50 thou that always does the trick.

Dean

If you're out of the lands, jumping the bullet, I was under the impression this would increase pressure???

Read the book, It lists max! You were over before the signs showed! If you insist on going into that territory.. watch the primers, ejector flow marks, measure just above the web and see if you have fast growth.

As far as I know the only manual with data for the 6.5x47 Lapua is the Berger manual, and I believe that is just quickload data, not tested data. Please correct me if i am wrong though. I started at 34.5 gns and worked up looking for pressure signs as I went to 37.7 gns. There was no flattening of the primers or ejector marks whatsoever. The firing pin is bushed so that may help with primer cratering etc...

I did look around prior to working up this load and it seems like the majority of people are running 37.5 gns or so of Varget, so I don't think I am that far over the max load. Would you please explain more about measuring above the web for fast growth. I still have the cases ( was brand new Lapua brass) that I can check. I am not sure exactly what you mean by the web. Thanks for the help.

Using the best data I can research for that load is my first step, if I'm way above known max, even without bolt lift etc, I will stop....

Otherwise I use bolt lift the most, because I may be using brass that I have already marked up--I keep working/using brass until it fails in some way....

I did research load data prior to working up the load. While the berger manual lists max at 35.8, it seems the majority of people are running around 37.5 safely. As i mentioned the bolt is not super hard to lift, just noticeably more than an empty chamber.

Thanks for the opinions guys.

[irondog54]

Skating in the area of max and over max is thin ice. Very little is obtained by doing so. I chased the max around for years, only to learn that 85% gave me better accuracy, longer brass and barrel life. The kills weren't underkilled, and no bullets bounced off of any animals. My 2 cents. If I need more out of say, a 30/06, I buy a 300mag...

[FUBAR]

Just like all rifles are different and what load works in one may be hot for another, data between published book can and does vary. Plus as you said, it does not always exist.

Couple of basic rules I learned early on:

Always start with the lowest published data...

Never load off of another's load data without researching/confirming the data...

I learned reloading from someone who had been loading since the 40's I think, and he use to measure the "pressure ring" with a micrometer to insure it never expanded in excess of 1 thou...

He also used a set of reloading "slide rules" called "reloading computers" and one could work out data, sort of the "Quickload" of the pre laptop days

Best of luck, and stay safe,

[FUBAR]

Ref: max to above max-- I have done ladder tests on many wildcats over the years that showed no "normal signs" of over pressure. If I established that I was over max, through reaserch and/or testing that others had completed, I backed my loads off.

I completely agree that more powder does not always equal more precision, and neither I nor the OP suggested it did.

[nubrun]

Ref: max to above max-- I have done ladder tests on many wildcats over the years that showed no "normal signs" of over pressure. If I established that I was over max, through reaserch and/or testing that others had completed, I backed my loads off.

I completely agree that more powder does not always equal more precision, and neither I nor the OP suggested it did.

That is correct, I am not advocating to exceed maximums just for the sake of pushing boundaries. My original question was simply how do you determine when you've reached the max for the gun/load combination. there are several signs/methods that I have seen and was just wondering what the consensus was.

[scope eye]

Reducing coal reduces pressure, it's kind of like what freebore does to a weatherby that's how bee's get there speed and bleed off pressure.

Dean

[Jamie]

If you're out of the lands, jumping the bullet, I was under the impression this would increase pressure???

If you are really close to the lands or in the lands that would help. You are correct though, recucing CAOL is reducing case capacity. Same amount of powder in smaller space equals more pressure.

Like others said, you have to rely on several factors when determining the max for your rifle. A lot of the Savage rifles I have had lately seems to have slightly oversized bushings and I get cratering with minimum loads. Flattened primers will tell you things as well as shiny pots on the case head. Hard bolt lift will tell you most times but if you have a really rough chamber then you may get a sticky bolt before you reach your max.

[MZ5]

Here's some good info about all the 'pressure signs' everyone knows about or watches, and how so many of them may not mean what everyone thinks:
http://www.shootersforum.com/handloa...ure-signs.html

The prudent thing is to stop at book-max charge or book-max velocity, whichever comes first.

[nubrun]

If you are really close to the lands or in the lands that would help. You are correct though, recucing CAOL is reducing case capacity. Same amount of powder in smaller space equals more pressure.

Like others said, you have to rely on several factors when determining the max for your rifle. A lot of the Savage rifles I have had lately seems to have slightly oversized bushings and I get cratering with minimum loads. Flattened primers will tell you things as well as shiny pots on the case head. Hard bolt lift will tell you most times but if you have a really rough chamber then you may get a sticky bolt before you reach your max.

I have heard about the slightly oversized bushing issue with rounds that utilize the small rifle primer, such as the 6.5x47, and as a precaution had the firing pin bushed by Gre-tan rifles. I have seen no cratering whatsoever, although looking at the cases again this morning, I did notice the most faint ejector mark mark at the higher charge weight. In order to see it you had to rotate the case at just the right angle to the light.

Also as advised earlier in the thread I measured the web area of the case, and measured the following:

New unfired case: 0.465"
34.5 gn fired case: 0.4685"
37.7 gn fired case: 0.4688"

The 34.5 gn load had no marks or sticky bolt lift, and is well under the maximum quickload charge information listed below and listed loads on different forums (which I know doesn't mean they will work in every rifle, but they do serve as a point of reference):
130 VLD Grain VARGET 32.0 2448 35.8 2700 94.2%

[helotaxi]

If you are really close to the lands or in the lands that would help. You are correct though, recucing CAOL is reducing case capacity. Same amount of powder in smaller space equals more pressure.

However, with a bottleneck rifle case, thanks to the relatively slow powders in use, the high engraving force that causes the greatest pressure rise and the relatively small reduction in case capacity from seating the bullet deeper, the pressure increase from seating deeper is usually more than offset by the decrease in engraving force (thanks to extra bullet inertia from the "running start" the bullet gets on the lands) and the net result is pressure decreasing as you move farther from the lands. You will eventually reach a point where the extra freebore doesn't help anymore and the reduction in volume takes over.

[FUBAR]

I have heard about the slightly oversized bushing issue with rounds that utilize the small rifle primer, such as the 6.5x47, and as a precaution had the firing pin bushed by Gre-tan rifles. I have seen no cratering whatsoever, although looking at the cases again this morning, I did notice the most faint ejector mark mark at the higher charge weight. In order to see it you had to rotate the case at just the right angle to the light.

Also as advised earlier in the thread I measured the web area of the case, and measured the following:

New unfired case: 0.465"
34.5 gn fired case: 0.4685"
37.7 gn fired case: 0.4688"

The 34.5 gn load had no marks or sticky bolt lift, and is well under the maximum quickload charge information listed below and listed loads on different forums (which I know doesn't mean they will work in every rifle, but they do serve as a point of reference):
130 VLD Grain VARGET 32.0 2448 35.8 2700 94.2%

The "pressure ring" which is right above the web and visible on most cases, is the area I learned to use as one of the indicators in ladder testing. I was always told that a .001 increase is the max--and I have read the same somewhere?

Good discussions,

[jsthntn247]

I rely on looking at the case head. When it starts to get shiny, I know I am getting too hot. You can also measure case head expansion and don't want anything over .001

[rusty815]

I look for two things, sticky bolt and extractor marks. I used to get flattening or cratering primers with relatively light loads, and because of that I don't use primers as a sign of pressure (unless its a blown primer of course). depending on the cartridge, I may get extractor marks before sticky bolt lift, or the other way around, but as soon as I get one I back it down by .5gr and use that as my max possible load, then I look at my targets to see where the accuracy nodes are and work from there.

[sharpshooter]

Varget is a touch too fast for that bullet. Try some H 4350.

[nubrun]

Varget is a touch too fast for that bullet. Try some H 4350.

H4350 was actually my original plan for load workup, but i can't seem to find it anywhere around me. I can find imr 4350 but have heard it is different.

Would varget be better suited with a lighter bullet. I was getting great accuracy with it sub 0.25moa.

[scope eye]

If you are going to use H4350 then try RL17 the results are usually better as far as FPS anyway.

Tanks Dean

[MZ5]

H4350 was actually my original plan for load workup, but i can't seem to find it anywhere around me. I can find imr 4350 but have heard it is different.

Would varget be better suited with a lighter bullet. I was getting great accuracy with it sub 0.25moa.

The IMR powder will work well, as most all IMR powders most always do. You are correct that it IS a different powder, so use IMR-4350 data, not H- data.

If Varget is working well for you, by all means keep using it. Just might want to give some thought to backing down the charges a bit.

[Jamie]

However, with a bottleneck rifle case, thanks to the relatively slow powders in use, the high engraving force that causes the greatest pressure rise and the relatively small reduction in case capacity from seating the bullet deeper, the pressure increase from seating deeper is usually more than offset by the decrease in engraving force (thanks to extra bullet inertia from the "running start" the bullet gets on the lands) and the net result is pressure decreasing as you move farther from the lands. You will eventually reach a point where the extra freebore doesn't help anymore and the reduction in volume takes over.

Isn't that what I said? Close to the lands it could help far from the lands it wouldn't and reducing COAL increases pressure.

Don't underestimate the pressure increase from reducing case capacity. It only takes 1 grain of powder to go from safe to stuck bolt.

[helotaxi]

Yes, but one grain of powder might be 2% or might be 4% of the total charge weight, while seating the bullet 0.050" deeper might only account for 1% of case volume. Obviously the bigger the bore with regard to the case volume the bigger a difference seating depth makes in case volume. Regardless, as far as seating the bullet deeper in the case goes, bottleneck rifle cartridges are not nearly as sensitive and straight-wall handgun cartridges.

[Jamie]

Lots of "might"s in that. At the end of the day, if you put 30 grains of powder in a case and put 30 grains of the same powder in another case that has less capacity, your pressure will be higher. You can see this in using different .308 cases from Remington and Winchester.


Back to the OP,

"Like others said, you have to rely on several factors when determining the max for your rifle. A lot of the Savage rifles I have had lately seems to have slightly oversized bushings and I get cratering with minimum loads. Flattened primers will tell you things as well as shiny pots on the case head. Hard bolt lift will tell you most times but if you have a really rough chamber then you may get a sticky bolt before you reach your max."