Ammo and AR10s

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12 years 6 months ago #13828 by Siscowet
Replied by Siscowet on topic Ammo and AR10s
13fcolt thanks for that explanation. It helps to get knowledgeable perspectives on some of this stuff. I keep steel cased stuff to weapons made to handle it.

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12 years 6 months ago #13845 by LebbenB
Replied by LebbenB on topic Ammo and AR10s

With .308 however, the cambering is opposite what most think. SAMMI .308 is actually the hotter load over 7.62x51. You can safely run the nato spec in .308, but a true nato spec chamber, an old school FN-FAL for example, may see issues running .308. This crossover is why much of the factory ammo is loaded soft and there is so much to be gained, performance wise, in handloads.


The above, while true, is not the real reason .308 should not be fired out of a 7.62 chamber. It's in the chamber headspacing. 7.62 is headspaced at 1.6355" while .308 headspaces at 1.6300". The small bit of difference comes from the fact that actual 7.62 brass is a bit thicker than civvie .308 cases. The danger in firing .308 out of a 7.62 chamber is that little bit of extra room allows .308 brass to stretch to it's shear point, potentially causing a case rupture (least bad) or explosion (most bad.)
The following user(s) said Thank You: Siscowet

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12 years 6 months ago #13848 by Siscowet
Replied by Siscowet on topic Ammo and AR10s

LebbenB wrote:

With .308 however, the cambering is opposite what most think. SAMMI .308 is actually the hotter load over 7.62x51. You can safely run the nato spec in .308, but a true nato spec chamber, an old school FN-FAL for example, may see issues running .308. This crossover is why much of the factory ammo is loaded soft and there is so much to be gained, performance wise, in handloads.


The above, while true, is not the real reason .308 should not be fired out of a 7.62 chamber. It's in the chamber headspacing. 7.62 is headspaced at 1.6355" while .308 headspaces at 1.6300". The small bit of difference comes from the fact that actual 7.62 brass is a bit thicker than civvie .308 cases. The danger in firing .308 out of a 7.62 chamber is that little bit of extra room allows .308 brass to stretch to it's shear point, potentially causing a case rupture (least bad) or explosion (most bad.)

Would this be especially true in reloads? On CTD 's review website, I have read some reviews of cases shearing off on one companies .308 reloads.

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12 years 6 months ago #13849 by 13fcolt
Replied by 13fcolt on topic Ammo and AR10s
oh I left out the headspace thing, good catch 11B.

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12 years 6 months ago #13925 by bgdv1
Replied by bgdv1 on topic Ammo and AR10s
ive been loading 168gr hornady amax with zero issues. i have a mix of brass ive been using. some win,fed, lc match, some military brass. i was weighing cases on my digital scale and all the lc, win and fed brass were within +/- 1 grain of each other. the military brass was +6 gr heavier wich was expected and i dropped off 1gr less in powder charge when loading it. guess what i was getting at i expected the lc match brass to be heavier than the win and fed brass.

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