So I'm doing the dummy round process with my new 260R barrel and it seems one of the lands extends further than the other 5. I'm trying to achieve the mythical .010-.015" jump associated with ELD bullets using the sharpie technique but I'm down to 2.76" and there is still one land that is barely touching the ogive.
Should I use this as the basis for the jump or where all 6 lands are touching?
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Question?
Are you full length resizing or neck sizing and have you measured bullet runout?
Meaning is it a bur on the rifling or runout causing the bullet to not touch all the rifling.
Or don't worry about it and shoot some cheaper bullets to break the barrel in and smooth up the throat. (And then chase the lands)
I haven't fired it yet. I'm using fl resized 7-08 brass.
Run out is a possibility. Talking about really light marks on the bullet.
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Here is a video on how to find the rifling, and this method works very nicely and it's one I like the most.
https://www.youtube.com/watch?v=TWmIwPwLyyg
and another method video....
https://www.youtube.com/watch?v=GmDi7v530Og&t=569s
I also recommend getting a bullet comparator to get a reliable / repeatable measurement.
If you use the method like on the video, I must add that once you find the measurement to the lands and set up the seating die to that measurement, pay no attention to any small variation of length of the COAL.
The seating die (if it's been made in the past 10 years) will ensure that the cartridge base to bullet ogive is consistent.
Meaning that the Open Tip Match bullets will vary in length because their tips are not 100% identical, but the seating die will make sure the measurement from cartridge base to bullet ogive is the same. And that's what really matters.
The plastic tipped bullets are more consistent in length so the COAL will not vary very much after seating them.
There are tools made to measure the bullet jump to the rifling. Tools like the Hornady AOL.
Wilco!
I had to cut the nut off my donor receiver so I'm doing all this work with sharpie marks on the barrel and receiver at the correct head spacing. The first video seems to make the most sense for my current application so I'll give it a shot!
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Interestingly, the dowel rod technique shows an oal of 2.845" to kiss the lands. Looks the the sharpie was lying......by almost .100"!
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I found that major changes occurred to the lands with the first bullet down the tube on a new barrel. I measured as you are, before and after the initial few rounds and documented big differences in distance to lands. I also had a camera to look down into the throat and saw how the start of the rifling was knocked down after just one shot.
In my Criterion barrel the new, never shot lands were more than twice as high as they were wide, presenting an odd view when looking into the throat with my camera. They had a partial 45 degree chamfer, but after a couple of rounds fired, they began to look "normal".
So don't bother measuring lands with your new barrel. Load well short of the lands and break it in thoroughly before doing any measuring you are going to want to depend upon.
JMHO. YMMV
Can anyone post accuracy results due to bullet seating depth? I am new to handloading and have read many times the importance of the seating depth but have not seen any results.
^It is mostly a trial and error process, based on what a certain bullet likes in a particular barrel^. It is mostly agreed we should first find the Optimum Charge Weight that our barrel likes. Then fine tune with jump. accurate shooter.com and other sites have info on the subject. It is somewhat an advanced reloading concept used after the basics are mastered. :-)
+1
Jump is typically a fine tuning deal only, IME.
I'm a firm believer in the theory that if it bleeds, I can kill it.
Yep I only measure the lands in the beginning to make sure I won't be jammed causing pressure issues. I go shoot +/- 50rds, give it a very light cleaning and re-measure for load dev. I start at 15 thou off find my charge and most of the time if it looks like an adjustment is need I try 5 thou each way and one of them usually tightens up the load that last bit. After that I shoot it till it stops shooting, Clean it and if it doesn't keep shooting I test velocity and increase charge as needed. If you get the same velocity through charge and it still doesn't tighten up than measure and chase the lands. If it's not shot out this method will keep it going for you. I determine my barrels shot out when my rounds no longer fit in the mag due to OAL or the barrel just will not hold 1/2 MOA (Competitive requirement).
Below a very good post by Erik Cortina of "Team Lapua USA" with over 95 pages of postings with questions and answers.Originally Posted by 71velle
Long range load development at 100 yards.
Erik Cortina
Team Lapua-Brux Captain
http://forum.accurateshooter.com/thr...yards.3814361/
Some of you have asked for more detailed instructions on how I do this. Here they are:
1. Find Jam by seating a bullet long on a dummy piece of brass (no primer nor powder) and apply die wax to the bullet ogive and record it's base to ogive length.
2. Chamber the round and close the bolt.
3. Snap the bolt open and measure the base to ogive measurement. If it is shorter than previous measurement, this is your jam. Do it a few times with different cases to make sure.
4. Load a known powder/primer/bullet combination. I load 4 of each powder charge in 0.5 gr. increments and seat bullets at jam - .020". I use one shot of each to get barrel fouled up and also keep an eye for max pressure at the same time. You can also use these rounds to break in a barrel if you are inclined to. If I encounter pressure on the hotter rounds, I will not shoot groups with the other loaded rounds and will pull bullets when I get back home. Do not shoot in round robin style because position and natural point of aim will be compromised.
5. Shoot 3 shot groups starting from lowest to highest. All groups are shot over a chronograph.
6. Examine target and find the place where consecutive groups line up vertically and ES is the lowest and speed increases the least from one group to the next.
7. Load to the middle of the powder node and do a seating depth test.
8. Load 3 shot groups starting from Jam - 0.005" all the way out to Jam - .040" in .003" increments.
9. When you find the seating depth test that shoots the best, load towards the longest side of the node to allow more room for throat erosion.
10. Final step is to load the new seating depth and load 5 shot groups in 0.1 gr. increments 0.5 gr. on each side of node (if pressure limits are not reached). This will cover an entire grain of powder and you will be able to pinpoint where the powder node starts and ends. In the summer, load towards the low end of the node, and do the opposite in the winter.
You guys are awesome!!!! Great resources, exactly what I needed..
Ok, so I'm not a shooter for a major manufacturer, or a top competitor at rifle matches, but over the years I have found something that keeps everything very consistent and it doesn't get any simpler. I just use a neck sizing die and seat my bullets just a hair long. Then when I chamber a round the bullet pushes back in the case just a little and seats with the ogive just touching the lands. I seat the bullet to it's final position with the bolt. Hard to get more consistent than that and about as simple as it gets. I'm also convinced this method provides consistent bullet start pressure taking neck tension for the most part out of the equation. Since I'm usually working up from scratch I've never had any pressure problems that I've read about that can be associated with "Jammed "bullets.
Just thought I'd throw it out there.
A good wife and a steady job has ruined many a great hunter.
And what if you have to eject the round? Sounds like you would end up with a mess of powder in your action and chamber... if you shoot on a range and in matches and a cease fire is called you are required to unload all ammo. That's when I see this becoming and issue. I have heard of this process with some FClass shooters and what not. Not the best for a field gun though in my opinion.
Again, I believe it works! Just not the best option for the field.
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How do your hot loads compare in weight to max book loads? I'm trying to understand the dreaded and feared pressure spike I keep hearing about from your practice. A lot of guys jam their loads, it seems to work for most of them very well!
This rifle will likely only be used by myself, deep in national forest land, with pre targeted mountain sides. The threat of having to remove a round without using a dowel rod isn't huge, if the jam juice is worth the squeeze.
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most bullets shoot better with a jump...even VLDs...can you make most bullets shoot jammed? YES! do bench rest guys and F-class guys jam bullets? YES! are you a BR or F-class shooter? most likely not. what has the second biggest effect on POI? charge/powder weight...next would be seating depth...next would be case prep...next would be neck tension...next would be primers and so on...the hole is deep...some ppl may want to argue what effects POI more or less but ive spent a LOT of time and shot out a few barrels doing actual field testing chasing accuracy and "THE PERFECT LOAD".
ill tell you the single biggest effect on POI is the shooter...if he is not capable of shooting tiny little groups day in and day out then how will he know if he has found the perfect load or if what he is doing at the loading bench is actually working? i am no super marksman and do not claim to be an expert on loading or shooting but i can go out and shoot pretty small groups pretty consistently...ive NEVER shot a bench rest match(but i think i will next season)i shoot F-class matches both 600yd and 1000yd...i also shoot long range varmint silhouette,PRS and short range tactical matches and though i shoot the same loads at all they are all a different style of shooting and take a different mind set.
now back to jamming or not jamming...
this is IMR4451 with a 107g SMK i was playing with a couple of weeks ago...
107g SMK .025 off the lands CCI 200 primers
#1...40.5g
#2...41g
#3...41.5g
#4...42g
this is a 115g DTAC seating .020 off the lands CCI 200 42g H4350 5 rounds at 100yds
this is the same day same load but the 115g DTACs are seated .038 off the lands 5 rounds at 100yds...and just so you know i was having a good day...
heres some 140g berger hybrids at .035 off the lands...
this is 10 rounds with 10 different charge weights...142g SMKs all seated .025 off the lands at 100yds...
i could go on but ive cluttered up your post enough and the point is that bullets DO NOT have to be jammed to shoot small groups.
^ "MM" ^, jamming the lands is a reloading technique practiced by shooters that measure their targets and groups in thousands with calipers. With the type of shooting You describe, are You going to take Your calipers with You to the national forest and mountain side? I agree with Lonewolf. There is no need for accuracy to supersede practicality or safety, in a given shooting situation.
This reminds Me of the current craze with high BC, boat tail, long range bullets. How much money is wasted by shooters buying these pills that will never shoot over 300yds, rendering the extra expense useless. "The colorful shiny fishing lures are designed to catch 'fisherman'".
I reload and shoot from the bench to develop loads that give Me a high level of confidence. When I take that rifle and load to the field, I forget all about that OCD, and put em all in a small pie plate! ;-))
Like Long Range I have spent hours at the reloading bench and firing line to find as close to ideal load and seating depth, but unlike him I do shoot BR and just a little variation makes a big difference in your score. When shooting at a 1/16th dot inside a 1/2 inch circle at 100 yards every little thing matters we are talking 1/4 inch consistency at 100 yards.
Now on the other hand my hunting rifles are 1 inch shooters at 100 leaves plenty of room for errors in judging distance, plus they are all light weight guns not made like my BR guns.
FROGGY
See profile for fire arms
Do it today there maybe no tomorrow
We find out today!
21 Fahrenheit isn't ideal for rl17 but I have a bunch of stuff loaded at different lengths plus 50 mild 100gr loads to break in the barrel. This will be the first savage I've built for myself so I'm also interested to see how well the combo of components work together as they were chosen based on my little experience shooting longer than 300yd. Should be fun.
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Rifle appears to shoot best with .005" jam. Still breaking in and cleaning, May tighten up head spacing a bit.
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What seating depths have you tried?
As far as breaking in I wouldn't waste a lotta time with that 15 rounds is more than enough.
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2.745, 2.800, 2.820, 2.850". The picture shows 2.800 to 2.850", left to right. The 2.745" wasn't worth a digital picture.
My oal to kiss the lands was 2.845", though I realized today while cleaning that I needed a lot more torque on the barrel nut. It's entirely possible my head spacing was changing the whole time I was shooting. I got it back together today the right way with a slightly tighter head space. Waiting for the flat white paint to dry then I'll put it back together and give it another shot tomorrow.
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this is my suggestion to you and a little info about reloading for a 260....take it for what its worth.
first like most cartridges the 260 has 2 very accurate speed nodes...actually 3 but the third one is hard on brass...first is 2700fps +or- a little...second is right around 2825 +or- a little...your shooting accurate 4350 at 38.5g with a 140g ELD and id be willing to be your only about 2550 maybe 2600fps...if you have a chrony use it and post up your speeds.
now with that said do you see the trend on your targets? if not ill point them out for you...the problem with how your going about your load development is that your playing with seating depth BEFORE youve found a good charge weight which is already giving you false readings. your thinking that your on the right track with seating closer to the lands by looking at the targets...BUT...in reality the closer you get to the lands the faster the bullet is shooting because your creating more pressure and in turn more speed so its NOT the seating making the load shoot better its the increase in speed making the load shoot better...make sense?...and the problem now is that you say your touching the lands at 2.845 and your best group is seated at 2.850 which is .005 into the lands so where do you go from there?
thats right...back to the loading bench no closer to a good load than when you started and wondering why....and unless your barrel came loose yesterday its not your head space.
now accurate 4350 is #118 on the burn rate chart so its just a little slower than H4350 which is listed at #116...also hornady is very conservative with their charge weights listed in their book and the biggest reason is their bullets have a long bearing surface.
your loads...the hornady book lists 41.7g as max with A4350 at 2700fps so this is what id suggest...start at 42g and work backwards down to 40.2g in .3g increments...id load 4 rounds of each ALL at .020-.025 off the lands..2.820(so youll end up with 28 rounds),start with the 40.2g load and shoot 1 ROUND over the chrony and continue up in charge weight but only shoot ONE ROUND FROM EACH CHARGE WEIGHT OVER THE CHRONY watching for pressure and watching what your chrony is telling you as well as how these loads are grouping
your target...set up the target with 8 dots...or 8 of the targets you have pictured...all level like in the pic and number them 1-8...start with target #1 and shoot one round from each charge weight at target #1 over the chrony...target #1 is going to tell you 3 things...speed,pressure and how this load is going to work.
now let the barrel cool a little and either shoot round robin style(if your pretty new to shooting...if youve been shoot awhile and can shoot small groups consistently then shoot 3 shot groups)...if shooting round robin start with target #2 and shoot 1 round of 40.2g then move to target #3 and shoot 1 round from the 40.5g load...continue until you have shot 1 round from each charge weight at each target...so you should have 1 hole in each target and 1 empty case from each charge...let the barrel cool a little and start over in the same order...40.2g at target #2...40.5g at target #3 and so on until you have shot all the rounds you have loaded.
if you choose to shoot groups then basically the same thing applies...shoot the 3 40.2g loads at target #2 then the 3 40.5g loads at target #3...shoot either 6 rounds(2 groups)or 9 rounds(3groups)at a time and then let the barrel cool a little...id suggest 6 rounds at a time as the barrel will cool faster between groups.
if you try what ive posted here report back with your results...i bet youll be happy.
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