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Posted: 3/10/2005 1:15:50 AM EDT
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I have an M1A that I had for a few years that I bought new. I didn't shoot it much and later sold it to my uncle. He didn't fire more than 20 rds through it while he had it. I bought it back a couple of days ago. When I originally bought it, I didn't know much about firearms. Since then I have learned a few things. One of the things that I have learned is what headspace is and how to check it. As you may have guessed, I checked the headspace on this M1A and it swallows a Forster 308WIN nogo guage with ease. As best that I can figure, I either need a longer bolt or a new barrel to correct this problem. If I try replacing the bolt, is there a way to know beforehand if the bolt is longer than the one I have? If a new barrel is in order, where can I get one of good quality? BTW, this barrel is a commercial barrel and not a USGI barrel. On another note, what are the chances that Springfield Inc will honor their lifetime warranty on this? |
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I agree. If you shoot the rifle, check the brass of your first round and inspect the primer. If it's still intact with no protruding showing, you'll be fine. However, the caviat is that you never shoot commercial ammo in it but only NATO 7.62 x 51. Commercial 308 requires a must closer headspacing than the NATO ammo for a lot of reasons that I won't go into. You can also purchase from Forster Gauges, a NATO military gauge called the "field reject gauge". If you rifle closes on that, Don't Shoot It! That means your headspace is beyond even the military dimensions and will be dangerous which is why the gauge is called a "reject gauge". Excessive headspace can only lead to bad things happening. IF your rifle is out of headspace, you'll first have the bolt replaced and recheck it. However, at that point, you may also have to replace the barrel to correct excessive headspace. This is best done by a good armorer who deals with this type of military rifle. I've had both items replaced on my Polytech and now I can shoot any kind of ammo I like including great deer-loads. Normally, however, I'd be stuck with fmj NATO ammo. Hope that helps. Rome |
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There is no evidence that a rifle slightly over on headspace is dangerous or "bad things will happen." It's out of spec for sure, but General Hatcher used a grinder to induce massively excessive headspace and couldn't get a rifle to blow up. Got wildly inaccurate for sure. Certainly SAMMI lawyers don't want any part of excessive headspace. Military units gage their rifles twice a year. If a field gage won't close the right is good to go. It may go over spec the next day, but no one will know for at least 6 months. Don't stay up nights worrying about this, I'll bet not .001% of shooters ever check this and we don't see problems. As noted earlier leave this "serious" discussion for the gun store commandos who seem to think the sky will fall...  You shoot 10,000 rounds a year? Slip in a field gage every six months. -- Chuck |
Do you remember which of his books that was in? I have his Notebook and the book on the Garand and I do not remember seeing that. |
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Hatcher's Notebook Chapter X. See especially page 248 (last paragraph on) and page 251-252. They took a M1917 (.30) out to 1.965" (y reaming the chamber) without problems. Field gage (reject) is 1.950". That's .015" over. Don't let headspace frighten you. Hardly anyone knows about it and there are literally no accidents caused by it. -- Chuck |
This is why you have to be concerned about headspace with any rifle, including the M1a: My Polytech was on the "edge" of compliance with the field reject gauge. Just a bit more and that primer would have popped and caused damage and certainly some discomfort. So it's important to make sure you rifle is within spec, with at least the field reject gauge. Rome |
That appears to be an ammo issue to me. Chuck is correct, in the real world headspace is truely a non issue. This does not mean that you cannot have an issue, but excessive headspace is not an uncommon situation. If it were, you would read about KB's in combat. Study the Garand and the hell it was put through in the Korean War (nevermind the grunts) and you will realize you have an ammo problem, not a headspace problem. |
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Of course anything could and should be considered when it comes to diagnosing problems with firearms. Unlike a car, it's not just going to break down and strand you on the side of the road, after all. It could injure you our your neighbor so I think we can all agree that safety is rule #1. Now, regarding this specific problem, I can most assuredly tell you that this was no ammo issue. That's a Portuguese NATO 7.62 x 51 round, one of the most reliable and sought after Nato calibers. I've shot thousands of rounds of it without so much as a hiccup in four different rifle. No, in this case, it was the rifle. The head space was so out of whack that when I replaced the bolt, I also had to replace the barrel as it would still close on a field reject gauge. My armorer replaced the barrel with a NM medium weight Barrett barrel and then reamed it properly so that not only will my rifle shoot the NATO stuff but also any commercial ammo I'd like, to. So, my poly will NOT close on a NATO field reject gauge or a .308 no-go gauge , only the "go" gauge. And, he confirmed to me that the extremely excessive headspace was most certainly what caused the primer to bulge and just about pop. You are correct in saying that the Garand is a robust rifle and truthfully, I've never personally read an account of one failing in the field. However, these gauges are made for a reason and headspace is certainly something we should be concerned about or it would be a non-issue. To take the "car" analogy further, it's like the bearings in you wheels. Most people don't give them a second thought but by gosh, they better be properly installed, lubed, and tightened with the appropriate amount of play in them or you'll be losing that wheel eventually. Headspace is usually ignored by most rifle owners except for guys like us who obsess about our rifles and their condition. So, when a spent shell exhibits a primer that's ready to blow, it's like finding a car whose wheels are about to fall off. Something is responsible and needs to be addressed. My poly had, admittedly, probably the worst headspace of any other one out there and needed the replacments to correct it. I'm glad I did it and now I've got a rifle that will last for another generation of collector after I'm gone. Rome |
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Bulging primers as shown above can easily happen if the bolt is opening too soon. This is caused by too much gas pressure at the port. The M14 system usually limits this quite well, it's much more common with the M1 which has no cut off. If the bolt moves back with lots of pressure in the chamber this can happen. Usually coupled with a rough chamber so the case wall is sticking but the bolt is moving aft. This looks almost 1/10th of an inch. No way a rifle with in-spec headspace will do this unless the bolt isn't closed all the way. It can also be caused by poor factory primer crimp. I've cleared loose primers from AR15 rifles several times. One of these wouldn't bother me. I'd try different ammo. Bad lots are not unknown. I'm assuming the Field Gage used was 1.6455? I'd appreciate a source for such a gage. -- Chuck |
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Chuck, you can contact them here: http://www.forsterproducts.com/Pages/products.htm However, you must "ask" for the "military NATO field reject gauge". They make it under contract for the US military pretty much exclusively. They will sell you one if there's any on the shelf. They're around $22 each.....very much worth it as the Nato gauge will work in any Nato 7.62 x 51 rifle, of course. Nice to have for the FAL as well as the M1a. Thanks for the info. Since my Poly has been totally overhauled and shoots moa easily, I'm no longer concerned about any future adjustments for quite a while. Rome |
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Gosh. I just re-read your initial post and apologize for not providing at least my opinion. I'll point out that I'm not an armorer nor do I play one on TV but I've spend the past four months overhauling my Poly and have gleaned a bunch of info you may find helpful. 1) I understand that a "normal" poly will swallow a ".308 no-go" gauge, even from new. That's because they were designed from the outset to shoot NATO ammo (7.62 x 51) and NOT comercial ammo. That gauge you used is for commercial ammo headspacing to be used in commercial rifles in .308 which require a much tighter headspacing. From what I've read, the M1a (M14) machinery was designed for Nato ammo, not commercial ammo so it's not surprising that the "no-go" gauge failed. NATO rifles have this extra "slop" to accomodate battlefield conditions and I'd suggest that your rifle will most probably fire NATO ammo just fine. 2) A replacment bolt won't be longer. The lugs, however, will be crisper and hold the bolt face closer to the breech thereby reducing head space. Bolts wear at the lugs....especially on the Chinese rifles (Poly and Norinco). It's a well documented design flaw and the Chinese never did anything about correcting it. However, the receivers are of very high quality. So, if you put in a new bolt, it should be hand lapped to fit and close properly without harming the hardening that was applied to it. It may....or may not reduce the head space so that it won't close on a "no-go" gauge. The variable here is that the barrel is not original to the rifle but a commercial refit. It's interesting that you have a new barrel but an original bolt. Usually it's the other 'way round or both are replaced and the breech reamed to accept all ammos. These Chinese rifles originally have chromed-lined barrels and will usually out-live the bolts. Why your barrel had been replaced (unless it was done to make the rifle more competitive) without replacing the bolt is a conundrum. In any event, anyone who would install a new barrel should have cut the breech so that it would accept both NATO and commercial ammo, similar to what my armorer did. 3) The only real way to know if your headspace is correct would be to find a "NATO Field Reject Gauge". It's used to check rifles "in the field" hense the name. I've posted a link to Forster and they can provide you with one if you ask. I've also PM'ed you. Please check when you have a moment. So, from your description, it would sound like your rifle is sound to shoot. My rifle was so far out of headspace that when it was in battery (round loaded in the chamber, bolt in battery) I could actually move the bolt back and forth about than 5/64" or about .078 ! It was actually that loose and was the cause of my problem. In my new setup, locked and loaded, the bolt is tight in the receiver with no looseness in any respect. I know that this is not an accurate way to check headspace but I did discover the looseness by accident. Take the rifle to the range, load one round, let the bolt fly home and fire it. Then inspect the empty case and see if the primer looks ok (not like my photo) and there are no bulges or other deformaties. If not, you're good to go. Hope that gets you started! Rome |
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It can also be caused by poor factory primer crimp. I've cleared loose primers from AR15 rifles several times. This would be my guess. I have fired thousands of rounds of Portugese, I know it's quality. However, it is military surplus, meaning, anything is possible. I have no shortage of experience with these rifles and this ammo. My guess is that if you run another 10k rounds of Port through the same rifle, you won't see it happen again. But hey.....what fun would AR15.com be without rumors, paranoia and urban legends? 
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You are correct in saying that the Garand is a robust rifle and truthfully, I've never personally read an account of one failing in the field. This isn't at all what I meant when I suggested studying the Garand's role in Korea. My point was to highlight most likely some of the most horrific firefights in American military history, it ain't the forgotten war for no reason. I doubt headspace was what the GI's were worried about. The same can be said of Vietnam and the absolute astonishing amount of rounds fired. I highly doubt any of us on this website will stretch the headspace so far on our range rifles as to where it would be a problem. I have a retired Navy guy that works for me from time to time, he was on that famous river that John Kerry took into Cambodia on Christmas. He said it was not uncommon to fire 50k plus rounds a day when they had Army personel on board. I wouldn't worry about headspace a whole lot. |
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