Using the M2 30.06 to measure muzzle wear question

[imarangemaster]

IIRC, 1/4" on an M2 Ball round is about 0-1 on a gauge, 3/16" is 1+, 1/8" is 2+, and 1/16" is about 3+. My Inland has a tad over 3/16" on an M2 Ball round, and shoots VERY tight groups.

[karl schmidt]

remember some carbines were subjected to a "shoot to destruction" test of 6,000 rounds
If nothing broke, the gun was cleaned, crated up and issued along with the rest. so barrel ware with the low pressure - low velocity round was evidently not an issue. Even with the 30-06 rifles there were no ord. dept. gauges or specs. to reject rifles for muzzle ware, Only throat erosion

[CrossedCannons]

Can't speak specifically to those 6K round "shoot to destruction" tests, but the endurance test described in my Ordnance Inspector Training Manual (SA-ITM-S201, 1951) required that

Carbines fired in [4500 round] endurance tests shall be scrapped by the contractor"

Lots were "passed" if not too many things broke during these tests. The actual "test" rifle was sacrificed, regardless

[INLAND44]

One more thing; an excellent barrel can still fail the bullet test or muzzle wear gauge if it has been roughly and improperly cleaned many times with a jointed steel G.I. rod. The government had a procedure for this which was to simply back-bore the muzzle to get to the good lands. You always check for a 'counter-bore' before accepting a bad muzzle wear indication.

[JimF4M1s]

I agree with that. I have two that eat my gauge but will shoot under 4" at 100 yards.

[painter777]

I-44 and JimF,
Agree 100%
On our way down to New Orleans (post Katrina) we looped by my good friends in Bhama. He brought out a counter bored carbine that shot (rested) groups as tight as 4"- 5" at 100yrds.
Can't recall the maker, but do recall it was the first counter bored carbine I had seen shot.
I couldn't see where you could ask for more out of the carbine.

I sold a late WRA barrel some years back that was slick clean inside. Though it had a pretty large divet between the lands (Ridges) down about 3" from the muzzle. Using my Poor Mans Muzzle Gauge, it still showed 1/4"+ exposed.
Only thing I could figure that could have damaged it was a jointed cleaning rod. Don't have it anymore, but at the time was even able to get a picture of that Divet. That divet was deep and elongated. Friend thought a possible drill gun and stainless cleaning brush went crazy. But as stated bore was super clean, unless if they had tried a brush/drill gun, maybe a brush could have broke off causing the damage.
But then..... Could've been a little of both, Damaged by the jointed rod, then a attempt to lighten it up with a spinning brush...........

CH-P7

[DaveHH]

SOME carbines that had completed the 6K tests were released for issue. Others were definitely not.

[painter777]

There you go Dave,
Now that looks real nice.

Thx,
Charlie