Throat, muzzle and crown on CMP M1's

F

ffs1942

New member
My service grade M1 came with an inspection tag that says the muzzle reading is 1+. Throat reading is 1+.

What does this mean?

I also note the crowning at the muzzle is pretty rough.
I only got 2-3" BR grps at 100 yds. This could be the ammo(civ 150 gr) or me. The groups moved nicely with sight adjustments and I'm still learning the gun.

Still, the crown looks quite raggedy. I'm tempted to clean it up my self with a hand drill and a small grinding ball. I've done this myself previously, but on muzzles that likely didn't need it anyway. The ball pretty much self centers and I turn the rifle periodically. Of cse, I go slowly and lightly.

Would CMP let an inaccurate crown out on a service grade?

Brian
Des Moines
 
Throat measurements measure the wear caused by gases burning as it pushes the bullet out the chamber and barrel. 10 is considered max and unservicabe. Your "1" is excellent.

Muzzle wear is cause by GI's running a cleaning rod improperly down the barrel while cleaning. The Army goes crazy on this cleaning crap.

My gage is out in the shop but I believe it goes from 1 - 4, indicating you have a goon muzzle.

Don't get to excited about it. According to the Gage's my M1 should be worn out but it still shoots under 3MOA and is capable of cleaning the Grand target. It just won't do it when I'm standing.
 
I only got 2-3" BR grps at 100 yds. This could be the ammo(civ 150 gr) or me. The groups moved nicely with sight adjustments and I'm still learning the gun.
Click to expand...

You're not using storebought hunting ammo are you?
 
The USN marksmanship unit rebarreled their match grade Garands when the gauge read 5; typically about 4000 to 5000 rounds. Your barrel's got a lot of life left in it.

Regarding the muzzle, I've seen no degradation of accuracy if an M1's muzzle is so worn form steel cleaning rods that there's no copper wash back for 1/2 to 3/4 inch. That's evidence that the metal's been worn away quite a bit. But its the same for every shot fired; doesn't hurt accuracy.

On the other hand, if the crown, the edge at the end of the rifling at the muzzle angled face is chiped or damaged, then a crowning tool will need to be used to clean it up.
 
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