Go Back   CMP Forums > CMP Sales > Ammunition
Register FAQ Members List Calendar Mark Forums Read

 
 
Thread Tools Display Modes
Prev Previous Post   Next Post Next
  #1  
Old 09-03-2014, 07:24 PM
normannewguy normannewguy is offline
 
Join Date: Dec 2009
Posts: 899
Default Cartridge & Headspace Specifications: .308 Win / 7.62 NATO

Ok, here are the specs again...

SAAMI .308 Winchester:
GO: 1.630 in.
NO-GO: 1.634 in.
FIELD: 1.638 in.


FN FAL:
GO: 1.6325 in. (FN & Brit/commonwealth. Canadian is 1.6315 in.)
NO-GO: 1.638 in.
FIELD: 1.640 in.


7.62 NATO (M14 US MILSPEC):
GO: 1.6355 in.
NO-GO: 1.638 in.
FIELD: 1.6445 in.


------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Chamber and cartridge drawings...

1. .308 Winchester:
Direct link: http://s1052.photobucket.com/user/f6...tml?sort=3&o=2





------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




2. 7.62 NATO:
Direct link: http://s1052.photobucket.com/user/f6...tml?sort=3&o=3





------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Both cartridges have the exact same external dimensions! The only difference between the two is usually the weight of the brass (generally due to thicker brass near base on NATO cartridge)...
- .308 Win SAAMI brass weighs in average between 155 - 165 grains.
- 7.62 NATO brass weighs in average between 175 - 188 grains.

Looking at the GO for SAAMI and NATO there is a .005 difference, which means there will not be a problem in using 7.62 NATO ammo in a .308 chamber.
Most US ammo companies who make NATO ammo (Winchester being one) produce to the minimum spec of 1.628 and hold it there, which allows it to be chambered in both.

The only time you run into a problem is overseas ammo companies who make ammo to NATO standards. They will let stuff go that headspaces at 1.633 to 1.635 which in a 7.62 NATO chamber is fine, but is .003 to .005 too large for a .308 Win chamber.

If you have a minimum chamber of 1.630, you can run into feeding problems with some NATO spec ammo but normally only overseas stuff, like PPU
.

Last edited by Big_Red; 12-27-2014 at 02:23 AM. Reason: Nit-picking / clarification
Reply With Quote
 

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 10:50 PM.