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Old September 19, 2015, 07:40 AM   #1
BoogieMan
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Muzzle and throat erosion numbers, Beretta Garand

I am familiar with the gage process and that lower numbers are less wear. What I dont know is how much wear does the gage reflect.
For example:
Throat gage reading of 2.5+
Muzzle 2.0-
I assume this would still be a service grade rifle, but would it still be a tight rifle? Are the gages at or very near zero when the gun leaves the factory?
In particular I am looking at a Danish Beretta "Crown" over "FKF" over "Nr."
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Old September 19, 2015, 09:14 AM   #2
mapsjanhere
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A friend has a couple of like new, surely never issued late 55 Garands, and both throat gage just under 2. I've never seen one gage 1 or below.
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Old September 19, 2015, 10:06 AM   #3
44 AMP
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You need to find a printed standard for the gauge and the rifle you are using. Sorry, I cannot help with that.

I suggest you look at the military tech manuals for (some of) that information.

I was a small arms repairman in the 70s (M16A1 era). We had a bore erosion gauge, and the shop manual for the rifle had instructions for its use.

However, with that gauge, the only reading was serviceable/unserviceable. The actual diameters were not measured, and frankly for our purposes, were irrelevant.

If the gauge said unserviceable, the barrel was replaced, and the rifle went back out. IF it said serviceable, the barrel was NOT replaced, and it went back out. The Army is funny like that....
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Old September 19, 2015, 11:07 AM   #4
BoogieMan
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I found a few articles on the gage after some more intense google time. According to the spec new barrels should have a muzzle gage of less than 1. Every line is linked to an average wear of 1000 rnds, or .001". The throat gage works the same way. With the throat gage its a double issue. Its not only linked to the diameter but also the depth that the throat was cut at the factory. Like Mapsjenhere said, many new barrels wont gage under a 2. So the one I am looking at is gaging a 2 should be pretty good. I can always cut off 1/4" and re-crown if accuracy isnt acceptable. To be honest most of my guns dont see that much use anyway. All my milsurp is an occasional fun day at the range. The only 2 that see a lot of use is my steel chooting 1911 and clay bustin A400. Point is that if I buy it at a 2 it will likely be 6-8 years or more before it wears to a 3.
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Old September 19, 2015, 12:39 PM   #5
jcj54
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TE I & ME

The military Throat Erosion gauge goes from 0 to 10, 10 is market "reject". Brand new barrels throat at 1.75 (a punch mark is on the gauge at this location). Barrel which check 5.5 to 6 are too worn for top accuracy. From 6 to 8 they will exhibit "combat accuracy" and generally hit a man size target out to 600 yards. 8 to 10 and the barrel usually will not group better than 36" at 200 yards.
As to ME, the military never had an erosion gauge. Most military amorers used the test of inserting dummy round bullet first in the muzzle. If the bullet went in to the case neck the muzzle was too worn to be servicable. Some individual came up with a tapered ME gauge.
A new barrel gauges less than 1. Anything worn greater than 2 has less than stellar accuracy potential, but will hold the 13" aiming black at 200 yards.
Hope this helps.
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Garand Specialist
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Old September 19, 2015, 04:23 PM   #6
Orlando
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First off there is NO military specs for muzzle erosion only throat erosion.
I have had unissued in wrap 1950's Springfield barrels that measure 2 on the muzzle so not all new barrels will gage less than 1
There is alot more that affects accuracy than just the barrel and no one ever talks about it. Stock fit/lock up. You can have a NOS barrel and a loose fit stock and the rifle never will group well
The proof of a rifle is on the range, I have had Garands with what some would consider high barrel wear to out shoot rifles with lower wear
Bottom line is dont get so hung up on what the muzzle and throat gages
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Old September 19, 2015, 07:11 PM   #7
F. Guffey
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I have barrels that measure 1 (?), new barrels that means the barrel can not have muzzle erosion or throat erosion. I make tapered gages, tapered pins etc..

I have flash hole gages, if I do not know the diameter of the flash hole before firing measuring after firing is busy work.

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