M1A Reloading Suggestions

[257Roberts]

I've been shooting, competing and reloading for over 25 years. I can't even remember the last time I bought factory rifle ammunition. I like to think I know what I am doing, but I am always playing with something new and learning at the same time. Right now I am struggling with two rifles, an RPA Quadlock and an M1A NM. I will address the RPA in another thread...

So this M1A, this is my first one, and I had no issues working thru once fired LC Match 82. Gun was in the 1MOA range with 175gr SMK. This time around however, I loaded up the same, now twice fired LC Match 82 with 168gr AMAX [what I had on hand] and now the bolt/op rod isn't closing all the way on all rounds. Had 3 or 4 go bang, had 5 or 6 go click. Firing pin is striking the Winchester primer, but not very much. Upon inspection, it appears the bolt is just barely locking, but the op rod isn't pushing forward its last 0.5" of "free motion" stroke. Had to use my rear leather bunny ear bag to knock down on the op rod handle to get it to unlock and eject. This gun is [new to me] but has been shot very little believe and I cleaned it pretty thoroughly before I started. Granted, maybe I didn't get it lubed very well or in the right spots, I am not sure. All that said, it will get another good cleaning and lube job now.

Upon inspection of brass everything appears in spec. 0.469-0.470 at the base, 0.336" loaded neck OD, 2.008-2.010 length.
However, checking the shoulder bump with my 0.400 tool, I am getting 1.629-1.630 length, still in spec for 308 Winchester [1.634-.007]. Comparing that with some of my Lapua brass going thru my Palma rifle, the shoulder on those is more like 1.625-1.626. So my gut is telling me this M1A has a shorter chamber and I don't have enough shoulder bump happening in my brass.

Is the best method to check actual headspace to use the "spent primer trick" barely starting a spent primer, close the bolt, then measure the shoulder length? From that point, I have read in an M1A that more like 0.003" shoulder bump is a good thing.

Can anybody provide some insight? Am I on the right track?

 

[akajun]

M1A’s and Garands are stretchy receivers in that the brass stretches more than a bolt gun or ar10
Get your measurements off brass fired in the gun and size back .004-5 from that dimension
Also check your case lemgth and trim to min dimensions

 

[joshb]

For my M1A, I resize and trim back to “factory specs”. I.E.- I measure an unfired factory round and mash the shoulder back to that shoulder dimension. I mainly shoot Sierra 168s with H4895 or Viht 135.

 

[chkunz]

Like akajun says, measure the fired brass shoulder and then bump back from there, I always used ~0.003 bump. Reload them three times and then scrap the brass, I started getting separations on the about fourth reloading. I also use a small base resizing die.

 

[danny]

I've been shooting, competing and reloading for over 25 years. I can't even remember the last time I bought factory rifle ammunition. I like to think I know what I am doing, but I am always playing with something new and learning at the same time. Right now I am struggling with two rifles, an RPA Quadlock and an M1A NM. I will address the RPA in another thread...

So this M1A, this is my first one, and I had no issues working thru once fired LC Match 82. Gun was in the 1MOA range with 175gr SMK. This time around however, I loaded up the same, now twice fired LC Match 82 with 168gr AMAX [what I had on hand] and now the bolt/op rod isn't closing all the way on all rounds. Had 3 or 4 go bang, had 5 or 6 go click. Firing pin is striking the Winchester primer, but not very much. Upon inspection, it appears the bolt is just barely locking, but the op rod isn't pushing forward its last 0.5" of "free motion" stroke. Had to use my rear leather bunny ear bag to knock down on the op rod handle to get it to unlock and eject. This gun is [new to me] but has been shot very little believe and I cleaned it pretty thoroughly before I started. Granted, maybe I didn't get it lubed very well or in the right spots, I am not sure. All that said, it will get another good cleaning and lube job now.

Upon inspection of brass everything appears in spec. 0.469-0.470 at the base, 0.336" loaded neck OD, 2.008-2.010 length.
However, checking the shoulder bump with my 0.400 tool, I am getting 1.629-1.630 length, still in spec for 308 Winchester [1.634-.007]. Comparing that with some of my Lapua brass going thru my Palma rifle, the shoulder on those is more like 1.625-1.626. So my gut is telling me this M1A has a shorter chamber and I don't have enough shoulder bump happening in my brass.

Is the best method to check actual headspace to use the "spent primer trick" barely starting a spent primer, close the bolt, then measure the shoulder length? From that point, I have read in an M1A that more like 0.003" shoulder bump is a good thing.

Can anybody provide some insight? Am I on the right track?

I mostly load for M14s, M1s and ARs. If you feel that your shoulder position is short enough for YOUR chamber, you might want to try a small base die for radial clearance. Also, I am not one of "Those guys" that thinks once you are shooting these kinds of firearms, it automatically means small base dies (it doesn't). You also do not need to crimp with sufficient neck tension. The ultimate test is to try the sized cases in YOUR chamber with a stripped bolt.

Danny

 

[fatelvis]

168 SMK loaded to 2.8” over 41.0 grns Imr 4895 or 40grns H4895. It WILL shoot well in your rifle.

 

[danny]

I mostly load for M14s, M1s and ARs. If you feel that your shoulder position is short enough for YOUR chamber, you might want to try a small base die for radial clearance. Also, I am not one of "Those guys" that thinks once you are shooting these kinds of firearms, it automatically means small base dies (it doesn't). You also do not need to crimp with sufficient neck tension.

Danny

168 SMK loaded to 2.8” over 41.0 grns Imr 4895 or 40grns H4895. It WILL shoot well in your rifle.

Should be a really good load. I shoot a similar load with plain old school 4895, the 175 SMK, and a tiny bit more powder.

Danny

 

[EOD Rob]

I have a NM that I reload for as well! Starting out, I had issue just like you are having. For me, two things were at play here. First, LC brass is super strong and has a tendency to rebound after sizing. Second, my NM chamber is super touchy with sizing. I have to bump the shoulder back .004 or more to get it to feed right. Danny has the answer for the biggest problem your having! Small base dies will allow you to go pass factory sizing. Annealing will help out with the rebounding as well.
If you cant find Small base dies, you can use a wet stone to (slowly) remove material from the bottom of your 308 die. I had to do this with a 7mm-08 build that I resized LC brass for. Worked out great.

 

[457ciSBC]

168 SMK loaded to 2.8” over 41.0 grns Imr 4895 or 40grns H4895. It WILL shoot well in your rifle.

My M1A high power load was 42.0 IMR 4895, molycoated 168 SMK and IMI brass.....shot really well

 

[dannyjbiggs]

Well...I think that it might be time to "break tradition", and purchase some "factory .308" ammo, and try them in your M1A...like a few rounds of M118, M852, or Fed .308 Match (168 gr). If the rifle performs flawlessly as it should with this particular ammo...your handloads might be suspect. If still a problem, might be time to replace the op rod spring?

 

[Bob3700]

Well...I think that it might be time to "break tradition", and purchase some "factory .308" ammo, and try them in your M1A...like a few rounds of M118, M852, or Fed .308 Match (168 gr). If the rifle performs flawlessly as it should with this particular ammo...your handloads might be suspect. If still a problem, might be time to replace the op rod spring?

Having worn thru 4 bbls competing with my M1A, I would say that Danny has the best idea. Take some factory rounds, fire them in your rifle and then compare the base to shoulder dimension. Take that distance as your "Zero" and bump your shoulders .003 to .004" back. That will provide all the clearance you need for reliable chambering. Don't forget to use a GI chamber brush to keep the carbon build up in the chamber under control. Shoot that rifle in low light and you will see the amount of "FIRE" that comes back out of the chamber as the brass is ejected! It's impressive.
If any of the brass you have been using is out of a different rifle, that is a potential source of your problem. The solution may be a small base 308 FL sizing die. All you can do there is give it a try and see what the results are. If you control the shoulder bump, the brass will last longer than three firings.
Last thought, don't purchase once fired LC brass unless you know for a fact that it was fired in a Match Grade M1A. A lot of that brass was fired in a machine gun and is a case separation waiting to happen.

 

[dsinfour]

With m1a you must full length the brass each time so it will feed right . As that rifle is tough on brass every time you pull that trigger. Later

 

[searcher]

I think you are right on track with the spent primer method. Then set back .003" to .004" as others noted. I'd NOT use a short base die unless you find you are having feeding problems. All that will do is reduce the life of your brass. How long your brass lasts will depend largely on whether it is new when fired in your chamber, whether you are using a short-base die and how hot you load. If using once-fired mil brass - the first sizing should be done with a short-base - but subsequent sizing should not unless truly needed to facilitate loading. If running your cases very hot and using small-base die on once-fired machine gun brass - expect three to four firings. If you use new brass, don't load excessively, use standard dies and have a match chamber, I'd expect 5 or 6 firings - maybe more, depending on brand of brass.

 

[NorCalMikie]

Spent primer method?? FULL LENGTH RESIZE and be done with it. The first time you get a "slam fire" will be your last time!!
M1As hard on brass??? That is an UNDERSTATEMENT!! Red hot brass being JERKED out of the chamber by the case rim?? I guess!!
If you shoot an M1A, you favorite range tool is the "broken case extractor".
Ended up getting one for every caliber I shoot and having a couple "custom made" just to have on hand.
Maybe 1000 reloaded rounds fired thru my Fed Ord POS and like a Timex watch, "Takes a licking and keeps on ticking". Wouldn't want to be down range when the lead starts flying. Over the years of shooting, you learn to speak M1A.

 

[Uncle Ed]

I have read that you can not accurately measure the fired case shoulder location on M14/M1A rifles. There is still gas pressure in the barrel when the bolt starts moving to the rear and the shoulder can move forward. Meaning the case headspace can end up longer than the chamber headspace.

Below Mr. Zediker explains the M14/M1A chamber and sizing requirements. Meaning the case shoulder needs to be bumped back more and the case body diameter "may" need the be reduced more. In another book Mr. Zediker tells you the case body diameter should be .003 the .005 smaller in diameter than its fired diameter. This allows the case body to spring back from the chamber wall and extract reliably.

RELOADERS CORNER: 5 SIMPLE STEPS TO M1A RELOADING SUCCESS​

Glen Zediker​

http://www.mssblog.com/2017/07/20/reloaders-corner-5-simple-steps-to-m1a-reloading-success/

Below three types of Forster .308 dies.

 

[chkunz]

I shot the M14 for 30+ years. I started each year with a new Gene Barnett barrel and shot ~5000 rounds per year. The load was always the same, 168 SMK, 41 grains of IMR 4895 and LC match brass. I bumped the shoulder of the fired brass by ~0.003. I used either Redding or RCBS resizing dies. In all that time I only had one reloading problem and that was solved with a small base die.

Try some M118 ammo. If you gun will not function properly with that ammo you have a gun problem. If M118 ammo works then you have an ammo problem.

 

[Dave Marshall]

To measure your chamber accurately, you need a set of steel go ,no-go gauges. If fooling around with fired brass and soft seated spent primers were an accurate method, every good gunsmith would use that method. They don’t. Trying to take accurate measurements with fired brass is like trying to measure lumber with a rubber tape measure.

That said, M1a’s are notoriously harsh on brass as primary extraction begins while the chamber pressure is still quite high. Back when LC .308 brass flowed like milk and honey from the US gov., it wasn’t uncommon for brass to get recycled after two or three firings at most. With a wide open breech so close to one’s face, it might be best not to push your luck.

 

[cem]

I can't tell you what to do. I can say that Zediker is almost always right but not always clear. Pays to read his newest first though I have everything myself. Precision Shooting taught me that I can't buy points with bench rest techniques when what I need is practice.

Notice that Forster National Match dies are not higher quality - it's all as good as it gets - but do by design bump the shoulder for gas guns.

Approach it with an open mind. For the gas gun folks start at day one even with 25 years on bolt guns. I find gas guns and bolt guns like iron and aluminum molds form habits that are internalized but don't in fact carry over.

Myself I have a reasonably complete set of .308/7.62x51 head space gages by thousands or so (Forster is cheaper P.T.&G. is nicer) and a Redding Instant Indicator for checking base to shoulder dimensions quickly and with good repetition. That's why I have a T7 along with several other presses; so I can leave tooling setup. I often use the expression that I am renting a tool when I buy it expecting to send it down the road when it's done it's job and I usually keep it. Wilson gages and the RCBS Case Master and lots of other things are handy.

​ Die Set : Bench Rest® Seater & Full Length Sizing for 308 National Match. 308 National Match "bumps" or sets back the case shoulder, thereby reducing headspace by .003 From the 308 Win. Case body diameter is the same as the 308 Win. Intended for use in bolt-action target rifles.

 

[Mad_Charlie]

M14 Forum

A forum community dedicated to M14 and M1A Rifle owners and enthusiasts. Come join the discussion about optics, ammunition, gunsmithing, styles, reviews, accessories, Modern, Devine, SOCOM, EBR, classifieds, and more!

www.m14forum.com

These guys live, sleep, and breathe M14/M1A's

 

[danny]

I can't tell you what to do. I can say that Zediker is almost always right but not always clear. Pays to read his newest first though I have everything myself. Precision Shooting taught me that I can't buy points with bench rest techniques when what I need is practice.

Notice that Forster National Match dies are not higher quality - it's all as good as it gets - but do by design bump the shoulder for gas guns.

Approach it with an open mind. For the gas gun folks start at day one even with 25 years on bolt guns. I find gas guns and bolt guns like iron and aluminum molds form habits that are internalized but don't in fact carry over.

Myself I have a reasonably complete set of .308/7.62x51 head space gages by thousands or so (Forster is cheaper P.T.&G. is nicer) and a Redding Instant Indicator for checking base to shoulder dimensions quickly and with good repetition. That's why I have a T7 along with several other presses; so I can leave tooling setup. I often use the expression that I am renting a tool when I buy it expecting to send it down the road when it's done it's job and I usually keep it. Wilson gages and the RCBS Case Master and lots of other things are handy.

​ Die Set : Bench Rest® Seater & Full Length Sizing for 308 National Match. 308 National Match "bumps" or sets back the case shoulder, thereby reducing headspace by .003 From the 308 Win. Case body diameter is the same as the 308 Win. Intended for use in bolt-action target rifles.

I have found Zediker to sometimes write about topics he is ill informed about.

Danny