quick .308/7.62 case ?

fl23in

ok i know that 7.62x51(nato) is not Tech. the same as .308 due to higher pressures. However are the cases JUST THE BRASS any diff? i will mic them but just wanted to know if worth taking the time to do it. Reason i asked guy game me 6 box's of 7.62 Winchester brass he was shooting out of his m1a

nemesisenforcer

for almost all intents and purposes, they are interchangeable, with the caveat that commercial 308 is loaded hotter than military 7.62 as a general rule. In most guns it's not an issue, the primary exceptions being HK/CETMEs wherein the violent ejection process might rip thin commercial brass rims off.

In an M1A, it shouldn't be an issue from what I've read.

jonk

As with most military brass, might be a tad thicker. Assume you should stop a grain or two off max loads until you verify.

nononsense

fl23in,

"However are the cases JUST THE BRASS any diff?"

If the cases are factory new, there will be little if any external dimensional differences.

However, if the cases have been fired then all bets are off since the semi-auto chamber of the M1A can be slightly 'roomier'.

If he has re-sized the cases then the other inconsistencies will result from the re-sizer dimensions, the button for the neck sizing and the brass spring back.

The dimensional differences between commercial and military/NATO brass are usually found on the interior resulting in some smaller case capacities from the military/NATO cases. This can be assessed by weighing empty cases with a fired primer, then weigh a case filled with water to the case mouth. Subtract to find the case capacity or the difference.

Be aware that not all chamber reamers by manufacturers of chamber reamers are managed with a perfect degree of consistency either. There is always the possibility of small variations in the reamer itself as well as the set up used when the chamber is cut in the barrel. One reamer improperly aligned with the bore will cut a chamber with different dimensions than the one which is perfectly aligned.

This is just for fun. Here are some examples of chamber reamer specifications from one manufacturer:

M852 precision military chamber
Shank 0.4370
Base Diameter 0.4700
Shoulder Diameter 0.4550
Neck-1 0.3430
Neck-2/Case Mouth 0.3430
Freebore Diameter 0.3095
Pilot Diameter 0.2990
Min. Chamber Length/Base-to-Case Mouth 2.0200
Base-to-Shoulder 1.3540
Neck Length 0.3120
Freebore Length 0.0750
Rim/Belt Thickness 0.2000
Shoulder Angle 20*
Throat 1.5*

.308 Palma Match
Shank 0.4370
Base Diameter 0.4690
Shoulder Diameter 0.4550
Neck-1 0.3400
Neck-2/Case Mouth 0.3400
Freebore Diameter 0.3085
Pilot Diameter 0.2970
Min. Chamber Length/Base-to-Case Mouth 2.0200
Base-to-Shoulder 1.3540
Neck Length 0.3090
Freebore Length 0.0750
Rim/Belt Thickness 0.2000
Shoulder Angle 20*
Throat 1.5*

.308 Win commercial
Shank 0.4370
Base Diameter 0.4700
Shoulder Diameter 0.4550
Neck-1 0.3462
Neck-2/Case Mouth 0.3442
Freebore Diameter 0.3100
Pilot Diameter 0.2990
Min. Chamber Length/Base-to-Case Mouth 2.0250
Base-to-Shoulder 1.3540
Neck Length 0.3210
Freebore Length 0.0900
Rim/Belt Thickness 0.2000
Shoulder Angle 20*
Throat 1*45"

7.62 NATO
Shank 0.4670
Base Diameter 0.4725
Shoulder Diameter 0.4560
Neck-1 0.3460
Neck-2/Case Mouth 0.3460
Freebore Diameter 0.3110
Pilot Diameter 0.2990
Min. Chamber Length/Base-to-Case Mouth 2.0250
Base-to-Shoulder 1.3560
Neck Length 0.3200
Freebore Length 0.1500
Rim/Belt Thickness 0.2000
Shoulder Angle 20*
Throat 2.5*

Best.