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Old July 25, 2021, 05:52 PM   #1
akinswi
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Crimping For M1 Garand

I know this is an old worn out subject, But Since Im here at work and not a soul around I would like to share my experience on this subject.

I wanted to run an experiment on loads for my M1 between no crimp, Taper Crimp and Lees FCD using both sierras 150 FMJ (2115) and 168 SMK (2200)

I also ran the test with annealed brass and non annealed after firing did not change the results. But I mainly anneal to expand case life not 1000 yard benchrest shooting either.

I shot over 500rds ranging from new brass to once fired. For me my best accuracy came from Reddings taper crimp die.

It (Taper Crimping)showed more consistent groups in both 150s and the 168s.

This test I used a lee full length resizing die and a forster full length resizing die. I wanted to use two different resizing dies too eliminate a difference with possible neck tension between the two dies. Since neck tension is really what is going on here. In other words 1 die may create different neck tension than the other. I wanted to make sure that my original Lee Die wasn’t giving me bad neck tension so purchased another resizing die.

I also removed the expander balls from both dies and then resized the necks afterwards using a lee collet die. I full length sized first, without expander ball then sized neck back with collet .

test results were same, Taper crimp die worked the best

Also in another test removed the expander ball and used lyman m neck sizer die to expand the necks and ran all three tests again. Again full length sized then ran neck sizer die.

Again same results, Taper crimp better results

The amount of Crimp was medium for both The Lee FCD and Redding Taper crimp. I also notice the taper crimp was way easier on the necks on the brass than the Lee FCD.

Again I dont want to start an argument and by no means was this a scientific test, Just guy trying a bunch of different things and seeing the results (to me this is the fun part of reloading.)

I know hundreds of thousands of rds have been loaded without a crimp for the M1 with great results, but rather I was wondering if anyone notice in there M1 if crimping gave them better results than not crimping . But When you see group sizes shrink 30 even 50% was eye opening for me.


But the bottom line in MY M1 with me shooting I shoot better groups with using a redding taper crimp die across a range of different types of brass and bullets.

Powder that was used was IMR 4895 and primers were CCI 250s. I used a COL of 3.250 for the 150s and COL of 3.320 for the 168s per Sierra Load data. I also used a Redding Competition Seater Die and used a Dillion BL550 press, each powder charge was weighed by hand. Trim length on brass was 2.484 +- .001 due to different manufacturers of brass I used.

Rifle , 1953 H&R M1 with original barrel the throat has not been gauged. All test shots were done from a rest and at 50yds.

I wanted to say special Thanks to UNCLENICK for answering all my annoying questions while I did all these tests.

Last edited by Unclenick; July 26, 2021 at 09:47 AM. Reason: typo fix
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Old July 25, 2021, 06:45 PM   #2
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I see a lot of info about what you did and how, but nothing saying HOW MUCH better the taper crimp loads shot than the others.

To me, that's the bottom line. Doing extra work for a tiny improvement is one thing, doing it for a significant improvement is something else.

So, if all you tell us is "shot better", that's not telling us anything that we can quantify.
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Old July 26, 2021, 05:40 AM   #3
akinswi
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44Amp,

For me, the gun would go from shooting a 2 inch group at 50 yards to shooting .5 inch group at 50 yards.

Best group I got using non crimped ammo was about .95 inch group with the crimp it was about .54 inches

So almost cutting the group in half was eye opening for me.

But with Factory ammo Like with PPUs 150 grain FMJ for M1 Garand it would shoot about an inch. So I knew something was going on with “MY” Reloading practice.

For Me there isnt any extra effort due to the crimp die on my press is the last stage.

So I hope it might help someone in the future who isnt getting great results and try something different because with these firearms you can go either way and see which works best for “That Person” and “ That Rifle.”

Last edited by akinswi; July 26, 2021 at 08:18 AM.
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Old July 26, 2021, 10:19 AM   #4
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I think he was also asking how much difference you saw between the Lee FCD crimp and the Redding taper crimp die. It would be interesting, since you have a baseline, to see what happens if you can test with light and heavy crimps as well as the medium ones.

The other thing to check, when you get an opportunity, is short vs. long-range accuracy. Sierra and Lee had a sort of advertising war going on in the '90s, with Lee claiming their FCD could produce best accuracy, and Sierra arguing anything that deformed their bullets in any degree was bad mojo. The war ended with Lee ads stating their crimp die could produce best accuracy with all bullets, except Sierra. I don't recall the exact phrasing, but it made it look as if the problem was with Sierra bullets rather than with the die. Pretty funny to watch. Anyway, since there is a little distortion involved (just as there is when putting a crimp cannelure in a bullet, btw, which is the reason match bullets don't have them), and the distortion is not to the bullet base, it follows that you may not see any adverse effect at shorter ranges, but when you get out to 600 yards you might detect a difference due to decrease in BC resulting from the distortion or due to slow radial drift due to slight asymmetry in the bullet due to the distortion. It's something worth checking if you get the opportunity.
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Old July 26, 2021, 12:42 PM   #5
akinswi
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Unclenick,

Sounds like a new project. Maybe try them at 100 or 200yards. That would be doubling the distance of the old test. I would love test at 600 yards just dont have a range here that long.
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Old July 27, 2021, 02:57 PM   #6
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That's a frustration of many shooters these days.
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Old July 29, 2021, 01:24 PM   #7
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A rule of thumb for most rifle accuracy tests, groups open up about 10% in MOA for each 100 yards past the first one.

Except when trajectory compensation happens with slower bullets leaving at higher angles above the LOS than faster ones caused by the barrel's vertical whip. Then groups at the target range will be smaller than those at about 60% of target range where they are biggest.

Regarding testing loads........

If you shoot several groups with each load, the most accurate one is sometimes the one whose biggest group is the smallest because it shows what happens when all the variables add up. Smallest groups can happen when the variables cancel each other out.

If you got best accuracy with crimped in bullets, that sometimes happens. People shooting highpower rifle matches producing the best scores with handloads never crimp. Arsenals quit crimping 30-06 match ammo after WWII. Commercial match ammo ain't got bullets crimped in place.

Last edited by Bart B.; July 29, 2021 at 07:14 PM.
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Old July 29, 2021, 09:28 PM   #8
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Bart B,

That’s exactly why I was so surprised in my results, But Im going to re run some test groups at 100 yds and 200yds and see what changes.

But I also wonder did Lake City in there Manufacturing process did they size there neck dia lets say .305 Or would they increase the neck tension down lets say to .3035 .

I still have some Lake City M72 National Match ammo from 1967 . But it would bug the heck out of me to dismantle even 1 round because that ammo is so gorgeous and it’s becoming more scarce.

I did notice that I had less neck tension when i sized my case neck with a lee collet die vs a lee full length resizing die. The expander ball sized my necks around .304 vs .305 on the LCD if i remember correctly when I measured..

May also try Lees Reduced diameter mandrel (.3035)

Last edited by akinswi; July 30, 2021 at 09:50 AM.
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Old July 30, 2021, 03:24 PM   #9
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If you pull the bullet on the NM ammo and pour the powder out and invert it (to keep solvent from dripping into the primer) and use a swab dipped in mineral spirits to wipe all the asphaltum (pitch) sealant out of the neck and then likewise get it all off the bullet, you will be shocked to discover the bullet now slips right into the neck freely. The sealant was responsible for all the bullet hold.

If you then want to reassemble to original specs, you can buy "liquid asphaltum" from Blick's or other art supply places for use as an etch resist on engraving plates. Paint it inside the neck with a brush and let it dry and then seat the bullet again.
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Old July 30, 2021, 06:49 PM   #10
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That’s interesting Unclenick!
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Old August 1, 2021, 10:19 AM   #11
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The most accurate lots of LC 30-06 M72 match ammo tested about 13 to14 inches at 600 yards in bolt action test barrels. 16+ inches in the best match grade Garands.

Rebulleting that ammo with Sierra 180 HPMK bullets would reduce groups by one half to two thirds.
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Old August 1, 2021, 11:03 AM   #12
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I have a box of M72 bullets with pull marks, the target shooter it came from wasn't going to use them after replacing them with MKs.
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Old August 1, 2021, 05:02 PM   #13
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Note that Lake City match bullets were about .3086" to .3087" diameter. It may have been based on the fact that best accuracy is achieved by the bullet's diameters be a little more than the barrel's groove diameter.

Most Garand barrels made in government plants were broach rifled. First barrel rifled by a new one would have about that groove diameter. Each successive barrel would have smaller groove diameters but I don't know much. When the broach wore down to when barrel groove diameter was about .3077" the broach was replaced with a new one.

Sierra match bullets are about .3082" and shot most accurate in barrels with groove at .3079" or less.
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