I have been participating in a wrinkled bullet accuracy test in another thread. My rifle for this test was a newly acquired CZ varmint weight 308. The rifle was virtually unfired. the first thing I did was to load 60 rounds of jacketed bullets to see if I could establish that I would not be wasting my time trying to get the rifle to shoot. Even though I was not using match bullets, I was able to establish an 8 group agg of .81". The wrinkled bullet test consisted of 75 rounds using one bullet and one powder charge in order to keep everything consistent other than the bullet quality. The pertinent part of that experience was that grand agg for all 75 shots (15 groups) was just over 2". That is not good enough if I am going to shoot this rifle in matches this summer. I am planning to shoot 12 different loads. Hopefully by applying a little experience and a little research, I can quickly find out what this rifle likes (or not as the case may be). THIS IS NOT A TUTORIAL OR A RECOMMENDED APPROACH TO ANYTHING. I just thought we might have fun seeing what story 12 groups from an “inexperienced” rifle could tell.
Production Class 308
- 11K Views
- Last Post 05 July 2016
Good shooting. I bet recoil is a little less brutal also (lighter bullet).
I will soon be rebuilding the deck on a 12' x 12' floating boat dock. One 12' decking board (1” x 5” round edge) cost $20.00 at Home Depot. Their are cheaper places to buy lumber.
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I am increasing the charge 1/2 gr for an upcoming match. That may help. I am pretty sure the highest shot was my fault due to faulty shoulder pressure. The group size is the same on the diagonal as it is vertically. I didn't have this vertical stringing in the groups in post 168. I trust A2400 more in this rifle but until I find some more I have to save my current stash for the upcoming regional match. I need to rebuild my deck the next two weeks so further testing will need to wait. I am just grateful to be trying to get under an inch rather than under 2 inches where I started in February. :)
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I can't help but notice the vertical stringing. Did you throw from a measure or weigh the powder charges?
4759 is hard to measure with even a accuracy of +/- .1 gr.
It's time consuming but, weighing is best.
Frank
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Excellent shooting, JHS ! You've made good progress over the course of this thread.
Re: stability. In theory, your bullets should be plenty stable.
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Different bullet and different powder - the same result. While it is only by .030, this is the smallest group I have shot with this rifle. HAPPY BIRTHDAY AMERICA. WE ARE LUCKY TO BE HERE.
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I didn't mention that I have switched to a softer alloy approx 60% 92-6-2 and 40% Pb. That change coincided with a 1/4” Improvement in the 10 shot groups. I never thought when I started this project 965 shots ago that I would be making soft RCBS 180 SP bullets for the next match.
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Those aren't all that sooty. I do not care for 5744, heats the barrel up too much. But some folks do pretty well with it.
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Here is what the cases look like with 17.5 gr of A2400. I am running low on A2400 so I am going to try 21 gr of 5744 this afternoon.
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I usually put the first three into the dirt or my sighter before a record shot. Keep upping that charge until the necks are just lightly smoked.
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I went to the range today. My purpose was to test 17.5 gr of A2400 rather than the 15.5 gr I have been using. The lighter load was resulting in heavily smoked cases. I also have been having trouble stabilizing the 311299 bullets with the light load. My hope was that a couple more gr of powder would be sufficient to stabilize the 311299. First let me say that the 17.5 gr load WAS NOT sufficient to stabilze the 311299s. I had a tight cluster of six and then 4 strikes from 1 to 2 inches away from the main group. Those 4 holes all exhibited so tipping. I also shot 2 - 10 shot groups using the RCBS 180 SP. The pictures below each contain 9 holes as this rifle continues to send the first shot from a cool barrel 2” out at 9 O'clock. The aggregate for these 2 - 9 shot groups is 1.18". This gives me 3 groups in the past 7 days with the RCBS 180 SP all of which measure between 1 and 1 1/4 inch. I will be trying a couple of spitzers in the near future as I doubt that this load is going to shoot much better than this.
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Joe BDid you see any bullet tipping indications on your tgts, particularly the very low velones? Twist rates on your 3 guns?Shooting was at 100yds, I presume. but what happens at 200yds or beyond? I do know from experience, for example, in BPCR, that my 16 twist 40-65, with a 1.375” long Snover bullet clocking 1250+, will be ok at 800yds, borderline at 900, then “spray and prayat 1K, with bullets showing tipping when/if they go thru the tgt.Bullet length is major factor. I can then shoot my 1.325” long Elliptical Minigroove same gun, and yes somewhat higher velocity, and it is now stable at 1K.JHS, noting your 12 twist , I suggest you try the Lyman 311291. Shorter, and also famous for being one of the most accurate bulletsbeltfed/arnie
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Velocity slows with distance but I am not sure that RPMs do. Can someone clear this up for me? Does a bullet lose stability a velocity decreases?
Jim
I've had no luck seeing stability decrease as velocity decreases. I've conducted tests reducing powder charges and seeing POI elevation change and haven't seen stability decrease yet. Here are examples:
VERY LOW VELOCITY LOADS The Savage Striker pistol in 308 Winchester with Simmons 2-6 scope shoots averages of 5 5-shot groups at 100 yards of less than 2”. The load is: 314299 bullet ~200 grains sized .312”, Lyman Super Moly lube, IMR4227, Rem. 2 1/2 LP primers, 2.790” OAL. Here are the results of the testing: “Elevation” is the location of the group center with respect to the target center. “Group” “ is the average size of all groups shot. All group size measurements with a plastic 1/10” graduated plastic scale, readable in .025” increments. Quickload MV data thanks to John Bischoff Drop” Group” fps Pressure 26 1744 33697 25 1691 30883 24 1637 28236 23 1582 25749 22 1525 23415 21 +1.375” 1.95 1468 21226 20 0 2.35 1410 19177 19 0 2.45 1350 17263 18 2.176 1290 15479 17 2.019 1229 13281 16 -1.4” 1.96 1167 12284 15 -1.625 1.8 1104 10866 14 -1.5 2.3 1041 9557 13 -.75 2.03 978 8330 12 -1.375” 1.825 914 7221 11 -.75” 2.6 850 6219 10 -1.5” 2.7 787 5318 9 -3.5” 2.1 724 4516 8 -7” 2.35 662 3804 7 -11.75” 2.7 602 3182 6 -16” 4.3 544 2646 3/24/10, M10 Savage 308 Win, 314299. ~200 gr., .3095”, WLP, IMR4227, 2.925”, Lyman Super Moly first groove lubed Grains Drop” Group” fps Pressure 20 0 19 18 17 16 15 14 13 12 11 10 -6.5 2.05 9 -9 2.45 8 -12.5 1.6 7 -16 3.25 6 -21 2.3 M54 Winchester, 30-30, CCI L.P., 311299, .312”, Lyman Super Moly, one groove lubed, 2.830”, IMR4227 Grains Drop” Group” fps Pressure 10 zero 2.9 9 -4.5 2.0 8 -8 2.25 7 -13 3.0 6 off the paper grains vel psi 5 596 2582 6 678 3215 7 763 3972 8 848 4861 9 934 5889 10 1019 7068 11 1102 8404 12 1185 9917 13 1266 11612 14 1345 13506 15 1422 15586 16 1497 17871 Conclusions: Reasonable group sizes result with velocities unreasonably low. The 10” twist barrel provides sufficient rpm to stabilize 1.2” long bullets at unreasonably low velocities. No key holing or greatly elongated holes were found down to 544 fps. Velocity has little effect on stability in this region. The Creighton Audette Ladder Testing effect was noted as velocities increased from 544 to 724 fps. Above 724 fps to 1468 fps groups stayed +/- 1.5” elevation. I can't make the groups wild at 100 yards with any load or figure out what's happening between 100 and 200 yards with 16/IMR4227.
joe b.
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Hi Arnie The problem with the 311299 may also be the length. I am having big trouble keeping them stable. I know I can drive them faster but it will need to be a fair amount faster to keep them stable at 200. HAVING SAID THAT, I AM NOT SURE THAT IS TRUE! Muzzle velocity sets the initial RPMs. Velocity slows with distance but I am not sure that RPMs do. Can someone clear this up for me? Does a bullet lose stability a velocity decreases? Jim
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JHS,You may not need a “custom” 311299.Lyman lists a 314299. Or look for an older lyman 311299.I have one that casts up in the 312 area.beltfed/arnie
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The 30BR probably has a much tighter throat compaired to the larger 308 NATO chamber. So bullet fit is more snug before ignition.
Smoked cases is a sign of lower pressure...cases not sealing and bullet not swelling to bore. Upping the powder charge or quicker burning powder will help bump bullet to fit large 308 NATO throat. Accuracy may improve?
I measured those RCBS bullets using a calibrated micrometer. Measurements with 20-1 alloy were .301-.3015 and .309-.3095. Casting with linotype alloy increases size .001 larger.
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Sorry Muley! I was a little cryptic yesterday. I was using 15.7 gr of A2400. Yesterday my cases were getting “smoked” even after being annealed last week. I am going to move up to 17 gr I believe. I reread all of my notes last night. I had some early success with 20 gr of 5744. I later drifted away from this load in the midst of what turned out to be rifle issues. Of course I still like 18.5 gr of 4759 but so far A2400 has been a little better. My rifle (a CZ) has a large bore. Jim Kobe (my patient gunsmith buddy) was able to easily slip a .3005 stud into the muzzle when we were recrowning the other day. When I slugged the bore, it measured .301/.309. The 165 sil bullet was about .2995/.309. The 311299 was .300/.310. The 180 SP is .3015/.311 and of course the NOE bullet is not a bore ride. I have shot .309 bullets in this rifle earlier. They did not do well. The reason I tried again was that the alloy for these bullets was softer. I like the fact that my groups are starting to look like groups. That sounds obvious but in my experience even a small group which doesn't look “right” usually means something is still wrong somewhere. this is a maddening game by the way. I am surprised that the 311299 has proven to be so unstable in this rifle. When it flies nose first, it produces the smallest groups. However, right now I don't think I can keep it stable to 200 yards without a dramatic increase in velocity and recoil. I have soaked up too much recoil over the years to enjoy shooting a 200 gr bullet at 2,000 fps any more. I have been thinking that a custom mold which drops a slightly fat 311299 with a flat nose might be just the ticket at about 1650 fps. I should mention that this rifle has a 1-12 twist. I am still saving most of my stash of 30 xcb bullets supplied by Larry. These are short enough and light enough so that they might be the answer here. I have been waiting to have everything but the bullet fixed before I use the rest of these up. OK I apologize for not being cryptic this morning.:coffee
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JHS, what powder are u using and what wgt? What is the diameter of the so-called to small bullets? Ed Krasney shoote a .3095 in his 30Br and gets very good accuracy.U may have to up your powder charge to keep the bullets from tipping. Keep up the good work
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Early in this process I stated my goal as a 10 shot group agg of 1.25” or less. It looks like I have one load and soon will have another which can meet that goal. I am going to continue to tweek and test but in my opinion it is unlikely that I can attain an agg of 1” or less.
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Finally the RCBS 180 SP. This bullet fits my rifle. Right now it would be my choice. That might change when I get the 311299s stabilized.
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Now the 311299. This bullet is not stable. I shot another group 2 hours later when it was 15 degrees warmer. That group was about 9". This is a pretty good group although some of the bullet holes exhibit slight tipping.
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