M1A reloading questions


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CSestp
April 3, 2012, 12:50 AM
Hey guys
after much reading. I have finally gotten ready to do my first reloading. During my reading I found that the M1A is kinda a brass monster, and that all the "preferred" recipes is 41.5 of IMR 4895 with 168 gr using Lake City brass. At least that is kind of the starting point. Here are my questions

1. If I cant get ahold of Lake City brass how should I start to adjust my powder? less more?

2. Have heard of people using the same brass (although it was the thicker LC brass) much more than just 3 to 4 times by measuring the headspace in their M1A's and adjusting there overall length to very very close to this. Although it hurts my ego to ask, how do you measure your headspace in your rifle?

and as always for the dimmer bulbs in the box pictures never ever hurts.

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Jimro
April 3, 2012, 01:53 AM
Start at 40 grains of 4895 and work up to 41.5 grains just to be sure that it works in your rifle.

You measure headspace in a couple different ways, but you'll need a caliper, a Wilson cartridge guage, and you can make one of these http://www.gswagner.com/headspacegage/headspacegage.html to measure your chamber.

Once you record the actual dimensions of your headspace measurement, set up your reloading dies to "bump" the shoulder of the brass back about .001" and you are good usually good to go. Except the M1A really is a monster on brass, and you should full length resize if you plan on using the magazine, for single loads you might get away with "bump sizing" the brass. "Bump sizing" is really only suitable for bolt action, falling block, or break action rifles (and really not so much for the latter two as a lot of people screw it up and have a hard time chambering).

And reload 4 times and chuck it. The extraction is what causes brass failure in an M1A more than the stress of resizing.

Jimro

SlamFire1
April 3, 2012, 11:31 AM
for single loads you might get away with "bump sizing" the brass. "Bump sizing" is really only suitable for bolt action, falling block, or break action rifles (and really not so much for the latter two as a lot of people screw it up and have a hard time chambering).


I do not recommend anything but full length sizing for M1a’s/Garands, and I recommend using small base dies.

Set up your dies with a case gage and size to gage minimum.

http://img.photobucket.com/albums/v479/SlamFire/Reloading/ReducedWilsongagemeasuringnew308bra.jpg

M1a’s, M1 Garands, M1 Carbines, and Mini 14’s all share the same basic bolt firing pin/receiver bridge configuration. On these rifles the firing pin is not retracted until cam down. Prior to then the free floating firing pin is free to wack the primer.

This is the point at which the firing pin tang engages the receiver bridge. The firing pin is fully forward and able to tap the primer.

Why this is important is primer sensitivity. If you have an overly sensitive primer the firing pin can tap it with sufficient energy to ignite the thing. If that happens you will either have an in battery slamfire or an out of battery slamfire. These events are very rare, but they happen. I have direct personnal accounts of slamfires in all these mechanisms, except the Mini 14. For that I have a posting from CE Harris claiming slamfires in Mini 14's.

http://img.photobucket.com/albums/v479/SlamFire/M1a%20and%20Garand%20Receiver%20Pictures/ReducedDSN6756SAM1areceivershowingb.jpg
With a tight case, a long case, the bolt is stopped prior to cam down as it crunch fits the case to the chamber. Given enough tries, with sensitive primers, the occasional M1/M1a has been known to slamfire. Pray it does not happen when the bolt lugs are not engaged.


This is a slamfire that happened with tight cases

http://www.snipercountry.com/HotTips/Slamfire.htm

M14/M305: I looked at my personal "slam fire" and here is what happend. I have a NM TRW bolt in a Norinco M305, I shot realoads that were made for and previously shot out of my G-3, the local hunting clubs range I shoot at does not allow magazines, or slings,(go figure) to be used.
My conclusion: headspace is really on the tight side after lapping the bolt in, the realoads even though full sized still had the H&K flutes on them and may not have seated all the way in the chamber, I used thin CCI Bench rest primers in tight PMC brass pockets that were seated real flat, and I had to load the round into the chamber and then close the bolt onto it which causes a higher bolt speed forward that if it would feed a round out of the mag. BAM, Slammfire ! Clearly not the Guns fault, but operator failure. The only damage that I found so far is a small deformation in the OP rod cam were the bolts giudewheel runs. I´ll take her to the range again and fire some factory FMJ out of a Magazine to see if the little deburring I did solved the problem.
The straight wall, no neck .308 case is in a special glass case I reserved for little reminders. This case also includes a 1" truck wheel nut and bolt that I stripped. It was stamped L for left hand thread, but in the heat of battle, what do I know.
"Ende"
Torsten <lasercon@dialup.globe.de>
Germany - Thursday, February 11, 1999 at 08:50:34 (ZULU)


You should also use the least sensitive primers in this mechanism. I recommend CCI #34’s or the Tula7.62 primers. Both are advertized as being “mil spec”. You absolutely do not want to use Federal Primers as they are the most slamfiring primer on the market. Stay away from any primer that is described as “thin skinned” or “more sensitive”.

This gentlemen’s experience confirms this:



http://www.usrifleteams.com/forums/index.php?showtopic=4824&st=15

17 Aug 2005


John,

Congrats on your great performance at Perry.

I had to vote "Other". I have just scanned all the posts on this thread so far, but did not see any comment about the primers I use, which are the CCI Mil-Spec primers. I use the CCI 41 in the 223 that I shoot in my AR-15 Space gun (the Space Beast) and the CCI 34 in my 6.5 CHiP wildcat that I shoot in my AR-10 (the Space Monster).

These primers were designed to require 50% more energy to set them off in the standard drop test. To give them this "toughness", they have a slightly thicker cup and a slightly different anvil geometry than regular CCI primers. I was also told by Alan Jones of CCI that the amount and type of priming compound used in them is the same as what is in their magnum primers of the same size, making the CCI 34 and 41 equivalent to the CCI 450 and 250 respectively

I use these primers for one reason: SLAMFIRE PREVENTION!

I have had one slamfire in my shootng career. It happened back in 1990 when I was shooting an M14/M1A and that experience was the basis for the first article I ever wrote for Precision Shooting. Back then, the CCI Mil-Spec primers were not yet available; and after some testing, I switched from using the Federal 210Ms to the Winchester WLR. I have never had another slamfire after that first one, but it was enough. I hung up the M1A in 1993 after legging out and went back to the bolt gun, but when I began playing with the AR-15 Space gun that I call the Space Beast, I immediately started to use the CCI 41s in the ammo for it.

There was a time when these primers were hard to find, I think because of military orders; but now they seem to be more available. I got my most recent batch from Graf & Sons of Mexico, Missouri.


Just some things to think about.

All the best, Randolph


For all rounds I recommend you full length resize in a small base die.

Clean your primer pockets.

Seat all primers by hand and verify that they are below the case head.

Use powders in the IMR 4895 burn rate, or use IMR 4895.

Seat all bullets LT 2.800". I seat my 168's around close to 2.750. You do not want to seat bullets to the lands or any such nonsense which will might delay bolt closure as the bullet is seated.

Always feed from the magazine. Press single shot loads into the magazine never drop a round in the chamber and drop the bolt on it.

ReloaderFred
April 3, 2012, 01:19 PM
SlamFire1 gave you good advice. Please heed it.

I measure headspace in my two M1A's using an average of 5 fired cases in an RCBS Precision Mic. In my M1A Standard, I can close the gas valve and fire a round like a bolt action rifle, manually ejecting the fired round. This gives me an indication of the headspace, without the action ejecting the round. The funny thing is, firing both ways gives me the very same reading in this rifle, contrary to everything I've read about the rifle and what the action does to the brass. I then set my sizing die so the shoulder is set back .003" from the reading of the Precision Mic. My brass lasts longer than 4 or 5 loadings. I get more like 7 or 8 loadings before I scrap the brass for these rifles.

In my National Match M1A, the gas valve can't be closed, so the readings are taken from brass that has been cycled through the action when fired. The readings are consistant for all 5 cases, using the same components and loading data, so I'm confident that I'm getting a pretty true reading of the chamber.

I carried the M14 the whole time I was in the Marine Corps. It's an excellent rifle.

Hope this helps.

Fred

P-32
April 3, 2012, 06:15 PM
Have heard of people using the same brass (although it was the thicker LC brass) much more than just 3 to 4 times by measuring the headspace in their M1A's and adjusting there overall length to very very close to this.

Is a $.04 cent piece of brass worth damage to your rifle? No, don't go over 3. When I got my 308 M1 back from the gun plumber, he had included instructions stating not to go over 3 reloads with the brass. I figure the plumber who is also a competitor would know what he is talking about. There was no distinction between GI or Commercial. Now I know a M1 Garand is not a M1A, but they are closely related.

You have gotten some very sound advice. By following advise similar to what is written in this thread, I have not had to suffer a slam fire in any of my service rifle gas guns, 308, ’06 M1 Garands and a couple of AR 15’s.

The only difference is I use Forester match dies for the 30's.

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