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Discussion Starter #1
I am a little confused on this ammo for an M14. Can an original USGI M14 shoot .308 ammo or does it have to use NATO ammo.
If not what is the difference between 7.62 NATO ammo and .308?
 

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Its not so much the ammo since current U.S. NATO stamped 7.62x51 ammo is dimensionally (externally), case-wise, identical to .308 Winchester. The problem lies in what kind of chamber you have. The original design specs (from all that I understand) of the NATO 7.62x51 cartridge were more "relaxed" shall we say for intents and purposes in terms of tolerances. Face it, many countries had to produce the stuff, so tolerances had to be a little more lenient. Now true milspec NATO 7.62x51 chambers are "longer" in terms of headspace. This allowed for the use of different countries ammo and the wider case dimensional tolerances of NATO 7.62x51 ammo. Today's rifles "should" (not saying "will", but should) efficiently chamber both current US made 7.62x51 and .308 Winny because no one in the US makes ammo that isn't a .308 Winny case, dimensionally. What Im saying is todays US troops out there with M14's and NATO 7.62x51 cut chambers are shooting essentially .308 Winny cases, dimension-wise, if the ammo they are shooting (i.e. Lake City) was produced in the US....

Now, if buying foreign NATO 7.62x51 is your groove, you "could" (not saying will, but could) run into problems (see next paragraph). You could also run into problems if your chamber is a true longer milspec chamber (why anyone would cut one for a civilian rifle is beyond me) and the .308 Winny case just gets lost in there. Meaning the distance from the firing pin to the primer is too great to initiate ignition of it. But like I said, todays U.S. troops are shooting it. So I dont see it as a huge issue...

The darker side of the problems that could happen (although very unlikely with new production 7.62) is you have a commercial .308 chamber and you actually come across a slightly oversized cartridge that gets jammed in there, but the bolt doesnt fully cam over. It will ignite and could blow up your gun. The chance of that happening is remote with current US made ammo, but with foreign ammo or older US milspec surplus, it could be a problem. The "crunched" case could cause massive chamber pressures and the bolt, not fully locked in its lugs, wont be able to withstand it.

SIDE NOTE: Most chamber/port pressure problems in the M14 are a result of powder used and amount as opposed to the case itself...

Ultimately, no one here can tell you what your rifle will or wont shoot safely, without you taking the recommended steps of measuring your rifle's headspace if it is a concern of yours.

When in doubt, check it out. Only you can do that, but I do ,however, challenge anyone to show me current production US made NATO 7.62x51 ammo or unfired cases that are not dimensionally the same as .308 Winchester. The walls of the case may be thicker on NATO cases, but externally, the dimensions will be the same....
 

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There is definately a dark side to 762x51 in a .308 chamber. I shoot lots of surplus 762x51 with a 1.631 headspace. I remove the bolt guts and chamber every round before taking it to the range. About 3% of the surplus ammo I have used will not allow the bolt to fully close. I have also came across rounds that were damaged in storage or transport. At least one of these rounds would have caused an out of breach condition, and it doesn't take much damage to a case if it's in the right spot. I'll post some pics if I get the chance, still have the rounds in question. I love my surplus but due to tight .308 chambers I suggest caution. I believe that jameslawson71 has described it well in his post.
 

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Discussion Starter #5
Ok, so if I understand this right, dimensionally they are same. The only difference is the head space (NADO is a little longer).

With that being said which way would be safer, shoot a .308 bullet out of a rifle set up for NADO or NADO ammo out of a .308

I am trying to get a policer officer friend to go deer hunting with me, but he doesn't have a deer rifle. He can check out a M14 from the station, but doesn't want to use a FMJ bullet. He would like to use some kind of nosler partition ammo, but we are having this discussion if a .308 will work fine from the M14.
 

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Ok, so if I understand this right, dimensionally they are same. The only difference is the head space (NADO is a little longer).

With that being said which way would be safer, shoot a .308 bullet out of a rifle set up for NADO or NADO ammo out of a .308

I am trying to get a policer officer friend to go deer hunting with me, but he doesn't have a deer rifle. He can check out a M14 from the station, but doesn't want to use a FMJ bullet. He would like to use some kind of nosler partition ammo, but we are having this discussion if a .308 will work fine from the M14.
Its not so much the "bullet" its the case dimensions and chamber dimensions....

Here check this out....

http://theriflemansmanual.com/308vs7_62.php
 

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Confusion abounds

My understanding is, since mil/NATO 7.62 brass is thicker at the base, therefore, theoretically producing higher pressure than Commercial .308. So confusion still abounds. How many folks on this forum actually shoot both .308 and 7.62 in a commercially available M1A? My bet is, quite a few.
 

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My understanding is, since mil/NATO 7.62 brass is thicker at the base, therefore, theoretically producing higher pressure than Commercial .308. So confusion still abounds. How many folks on this forum actually shoot both .308 and 7.62 in a commercially available M1A? My bet is, quite a few.
Internal dimensions only matter in terms of amount of powder used (see next paragraph), thus it matters in terms of topic of handloading. There is no "direct" correlation between chamber dimensions and case wall/web thickness, because the thickness is on the inside of the case. (again see next paragraph).

Now, that said, a point can be made that given a "larger" milspec NATO 7.62 chamber, a thick walled case has more room to expand (as opposed to a .308 Winny chamber), thus giving more space for the burning powder to burn and keeping pressures in check, but this is usually "fixed" by loading military brass at a lower charge weight. [NOTE: I have never seen or heard of new, or even older surplus, US production NATO 7.62x51 (like Lake City) blow up in an M1A with a .308 Chamber].

I have fired everything from Hornady Match to LC M118LR to Federal American Eagle to LC Match to Winchester 7.62 White box to Hornady Tap to Handloads to M80 Ball to Federal Gold Medal Match to Black Hills, etc. in standard M1A Springfield cut .308 Chambers. I check the cases in a case gauge, at least a good sampling, and they always fit unless the case was externally damaged in some way.

The lesson is this.

1) If you are concerned about case fit, "headspace", check it. Dont debate it, dont theorize about it, check it. Then you will know. Same goes for cases if they are of questionable dimensions. My personal opinion is that any M1A/M14 owner should acquire the tools and skills to do this one task....

2) When handloading military brass, like LC, start with a lighter powder charge. Minimum .5 grs less than a safe weight you have been using for commercial cases.

3) Always check once fired cases, fired from an unknown rifle, in a case gauge. Even if they were sold as cleaned up and resized. Check them ALL!. You dont have to thank me, because you'll never have a problem concerning unknown once fired brass...

4) Stick with current production US made ammunition that is suitable for the rifle in terms of burn rate. Remington, no-frills hunting ammo from Walmart is probably not. The burn characteristics of the powder are probably not right for a gas gun...

5) If you want to get a deal on some foreign surplus, at a minimum, check the cases in a case gauge. There is no guarantee it will not be overpressured for your rifle, but if thats the route you choose, then you choose to take those chances... Some is good stuff, some will blow your rifle apart and could take a finger or an eye with it.

6) Do NOT shoot steel cased ammo in a 14. The extraction forces are too high and steel does not behave like brass. It does not contract the same, or in time, or at all, NOTE: just because your AK shoots it, doesnt mean squat. The speed of an M14's extraction operation is about as fast as they come in the gas gun family. Dont use it!
 

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Internal dimensions only matter in terms of amount of powder used (see next paragraph), thus it matters in terms of topic of handloading. There is no "direct" correlation between chamber dimensions and case wall/web thickness, because the thickness is on the inside of the case. (again see next paragraph).

Now, that said, a point can be made that given a "larger" milspec NATO 7.62 chamber, a thick walled case has more room to expand (as opposed to a .308 Winny chamber), thus giving more space for the burning powder to burn and keeping pressures in check, but this is usually "fixed" by loading military brass at a lower charge weight.

I have fired everything from Hornady Match to LC M118LR to LC Match to Winchester 7.62 White box to Hornady Tap to Handloads to M80 Ball to Federal Gold Medal Match to Black Hills, etc. in standard M1A Springfield cut .308 Chambers. I check the cases in a case gauge, at least a good sampling, and they always fit unless the case was externally damaged in some way.

The lesson is this.

1) If you are concerned about case fit, "headspace", check it. Dont debate it, dont theorize about it, check it. Then you will know. Same goes for cases if they are of questionable dimensions.

2) When handloading military brass, like LC, start with a lighter powder charge. Minimum .5 grs less than a safe weight you have been using for commercial cases.

3) Always check once fired cases, fired from an unknown rifle, in a case gauge. Check them ALL...

4) Stick with current production US made ammunition that is suitable for the rifle in terms of burn rate. Remington, no-frills hunting ammo from Walmart is probably not. The burn characteristics of the powder are probably not right for a gas gun...

5) If you want to get a deal on some foreign surplus, at a minimum, check the cases in a case gauge. There is no guarantee it will not be overpressured for your rifle, but if thats the route you choose, then you choose to take those chances... Some is good stuff, some will blow your rifle apart and could take a finger or an eye with it.

6) Do NOT shoot steel cased ammo in a 14. The extraction forces are too high and steel does not behave like brass. It does not contract the same, or in time, or at all, NOTE: just because your AK shoots it, doesnt mean squat. Dont use it!
Great info. Thanks
 

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I am trying to get a policer officer friend to go deer hunting with me, but he doesn't have a deer rifle. He can check out a M14 from the station, but doesn't want to use a FMJ bullet. He would like to use some kind of nosler partition ammo, but we are having this discussion if a .308 will work fine from the M14.
Hunting with an M14... FRG1FRG1FRG1
 

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Hunting with an M14... FRG1FRG1FRG1
It will work just fine, but make sure the Bullet is not over 180grs, I load 150gr Sierra Game Kings for my Son in Law who keeps me in Venison!
 

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It will work just fine, but make sure the Bullet is not over 180grs, I load 150gr Sierra Game Kings for my Son in Law who keeps me in Venison!
Trung Si, That is the best deal I've seen here today. Had a good deal worked out with my dad, if I brought home a lot of fish, he'd clean them and get half. That wasn't a bad deal either. dozier
 

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Discussion Starter #13
1) If you are concerned about case fit, "headspace", check it. Dont debate it, dont theorize about it, check it. Then you will know. Same goes for cases if they are of questionable dimensions. My personal opinion is that any M1A/M14 owner should acquire the tools and skills to do this one task....
Ok, so what is the proper tools to buy and where is the best place to get them.

Sorry, I am new to all of this.......
 

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Get McKee and Kuleks book M14 Complete Assembly Guide. Good book to have anyway. - Fulton Armory...

You need a GO and NO-GO headspace gauges for .308 Winchester if thats whats marked on your barrel or if you have a real GI Chamber marked (7.62x51 NATO) on your barrel you need ordinance gauges. Start with the .308 Win gauges. If the bolt closes on GO and not on NO-GO, you are GOOD-TO-GO for 308 Winny and just about any other US Made cartridge - Brownells, Pacific Tool and Gauge....

A Bolt Dissassembly Tool. You can get by without, but I dont advise it..

I would start by getting the book and reading the whole thing to get a better idea about your rifle in general. There is tool recommendations in there....
 

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Discussion Starter #15
Thanks to all,

I am a little bit clearer on the topic now. I will start with some gauges/books and go from there.

I might need help in the future if I can't figure this outGI6
 
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