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Posted: 11/6/2015 7:40:13 PM EDT
New to the 308 caliber. I recently purchased a Springfield M1A scout squad . The label on the box says 308 scout but the tag on the rife states that it was head spaced to 1.632 according to GI specs .this headspace requires ammunition that meet GI specs .what ammo caliber should I feed it, 308 or 7.62?
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You most likely will never have any headspace trouble running any commercial ammo sold as .308 win fmj or 7.62x51. You do need to watch the commercial hunting ammo as it may use an powder with the wrong burn rate for your gas system.
Factory new ammo is general extra small in headspace dimensions. The industry standard for factory ammo is on the small side because they can't know exactly what chamber you'll run it in. They won't make their ammo to be an exact fit for the minimum cut of a chamber. You may find some military surplus from foreign nations that could creep up to your 1.632 headspace dimension. A nato min chamber is only 1.6335 or 1.634 depending on the nation. (numbers off the top of my head, the 4 place one might be the match rifle min headspace) Your commercial ammo out of the box is likely down around 1.628 or even less. Any of your commercial FMJ loads should be M14 safe; your UMC, USA, American Eagle (Rem, Win, Federal respectively). |
| After doing some research,here what I found. "1.632" headspace will allow the shooter to use either commercial .308 dimensioned ammunition or NATO specification 7.62X51 without overstressing the cases too bad or creating an unsafe and potential possible out of battery issue when trying to shove larger 7.62X51 dimensioned ammunition in a too tight commercial .308 chamber." |
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Quoted:
You most likely will never have any headspace trouble running any commercial ammo sold as .308 win fmj or 7.62x51. You do need to watch the commercial hunting ammo as it may use an powder with the wrong burn rate for your gas system. Factory new ammo is general extra small in headspace dimensions. The industry standard for factory ammo is on the small side because they can't know exactly what chamber you'll run it in. They won't make their ammo to be an exact fit for the minimum cut of a chamber. You may find some military surplus from foreign nations that could creep up to your 1.632 headspace dimension. A nato min chamber is only 1.6335 or 1.634 depending on the nation. (numbers off the top of my head, the 4 place one might be the match rifle min headspace) Your commercial ammo out of the box is likely down around 1.628 or even less. Any of your commercial FMJ loads should be M14 safe; your UMC, USA, American Eagle (Rem, Win, Federal respectively). Thanks for the quick reply. |
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Quoted:
After doing some research,here what I found. "1.632" headspace will allow the shooter to use either commercial .308 dimensioned ammunition or NATO specification 7.62X51 without overstressing the cases too bad or creating an unsafe and potential possible out of battery issue when trying to shove larger 7.62X51 dimensioned ammunition in a too tight commercial .308 chamber." Yep, the only issues I ever recall hearing are some guys had some issues with overlength milsurp ammo. Most of which was long since shot up. I can't remember which nation's 7.62 ran to the long side. I've used British, South African, Belgian, and German foreign milsurp without any issues. ETA; you're welcome. |
Simplify your life and ignore the trivialists, many of whom will immediately rebut this note (with trivia, of course). 
7.62 NATO is merely the military designation for .308 Winchester. And vice versa. Which one came first doesn't matter. As our future President would say "What difference does it make?" It's easy to convert 7.62mm NATO to .308 Winchester. Been done for years. The conversion consists of the highly technical process of pasting .308 labels on each box of 7.62mm NATO. Pretty sure I still have a couple of cases of South African and Radway Green stashed away. 7.62mm NATO requires a specific bullet mass (nominal 147grain) at a specific muzzle velocity. .308 Winchester can be anything. Difference in the cartridge, not the headspace. There is technically no "7.62mm NATO headspace spec." (Nor 5.56mm NATO either.) There is a spec for the M14 rifle which also happens to be 7.62mm NATO. There are various machine guns which also fire this cartridge and they have different headspace specs. 7.62mm NATO out of a self loading rifle needs looser spec than out of a bolt gun and machine guns need even looser. -- Chuck |
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Quoted:
Simplify your life and ignore the trivialists, many of whom will immediately rebut this note (with trivia, of course).
7.62 NATO is merely the military designation for .308 Winchester. And vice versa. Which one came first doesn't matter. As our future President would say "What difference does it make?" It's easy to convert 7.62mm NATO to .308 Winchester. Been done for years. The conversion consists of the highly technical process of pasting .308 labels on each box of 7.62mm NATO. Pretty sure I still have a couple of cases of South African and Radway Green stashed away. 7.62mm NATO requires a specific bullet mass (nominal 147grain) at a specific muzzle velocity. .308 Winchester can be anything. Difference in the cartridge, not the headspace. There is technically no "7.62mm NATO headspace spec." (Nor 5.56mm NATO either.) There is a spec for the M14 rifle which also happens to be 7.62mm NATO. There are various machine guns which also fire this cartridge and they have different headspace specs. 7.62mm NATO out of a self loading rifle needs looser spec than out of a bolt gun and machine guns need even looser. -- Chuck I guess that's why you have 7.62 NATO gauges and commercial .308 gauges, huh. |
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FWIW my Bush rifle tag says the rifle has been headspaced to GI specs. The tag dated 3/25/95 says 1.63 with no other numbers. It has fed a bunch of Remington 150 coreloct softpoints, and many rounds of Aussie F4. Federal 155 palma loads were more accurate than the 168 FGM loads.
Paladin |
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