Rifle bores?

[garrettbragg12]

Being new to the family of Garand and Carbines collectors, there's allot I still need to learn, this one being very important. How do you judge a "good" rifle bore compared to a "bad" rifle bore?


M1/M3 Carbine: late '44 Inland
M1 Garand: late '44 Springfield

Information

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[imarangemaster]

Carbine barrels seldom have a serious pitting problem in the bore, since Carbine ammo was never corrosive. I have seen them frosty but they still shot well. The biggest problem with accuracy is muzzle errosion, usually from cleaning with GI steel cleaning rods. Once the ME is above "3" accuracy tends to drop off. Using a USGI M2 FMJ 30-06 round stuck in the muzzle, 1/4" of the projectile is about an ME of 1 or less, 3/16" ME2, 1/8" ME 3, and 1/16" ME 1 (approximately)

My un-messed with Inland ME <1



CMP Inland I had ME @ 1.5 - 2

[garrettbragg12]

Carbine barrels seldom have a serious pitting problem in the bore, since Carbine ammo was never corrosive. I have seen them frosty but they still shot well. The biggest problem with accuracy is muzzle errosion, usually from cleaning with GI steel cleaning rods. Once the ME is above "3" accuracy tends to drop off. Using a USGI M2 FMJ 30-06 round stuck in the muzzle, 1/4" of the projectile is about an ME of 1 or less, 3/16" ME2, 1/8" ME 3, and 1/16" ME 1 (approximately)

My un-messed with Inland ME <1
https://www.milsurps.com/images/impo...62712197-1.jpg


CMP Inland I had ME @ 1.5 - 2
https://www.milsurps.com/images/impo...ndmuzzle-1.jpg

I appreciate the photos. That helped allot. Thank you!


M1/M3 Carbine: late '44 Inland
M1 Garand: late '44 Springfield

[imarangemaster]

You're welcome. BTW, I LOVE your M3!

[JimF4M1s (Deceased)]

You have Garands, so a cartridge is no problem. Folks who don't can get a gauge.

[CrossedCannons]

The biggest problem with accuracy is muzzle errosion

While a barrel's muzzle wear may (or may not) affect accuracy, a bent bore certainly will. The metal of a carbine's barrel is fairly soft.

[garrettbragg12]

You're welcome. BTW, I LOVE your M3!

Thanks! It's been a fun project, and it was exciting to see the final product and show it off to people!


M1/M3 Carbine: late '44 Inland
M1 Garand: late '44 Springfield

[INLAND44]

Being new to the family of Garand and Carbines collectors, there's allot I still need to learn, this one being very important. How do you judge a "good" rifle bore compared to a "bad" rifle bore?


M1/M3 Carbine: late '44 Inland
M1 Garand: late '44 Springfield

The bore should look new. The barrel should be straight. By 'new', I mean mirror bore with distinct rifling. There are quick checks for bent barrels in the military manuals for each kind of shoulder arm. Then there is the muzzle wear indication. Throat erosion in the rifle calibers comes into play and there are visual checks and gauges for that. Of course, the chamber must be clean and without visible damage, and don't forget the cosmetic appearance of the finish on the barrel.
Going back to the bore, if you're looking at used long arms at a store or show, insist on having the bore dry-patched - sometimes oil can hide a lot. Pitting comes in two types; the 'frosty' kind that consists of thousands of small pits, giving the bore a darker, less bright appearance. If the rifling is distinct, such barrels will usually shoot to mil-spec, and typically the pitting fills up with copper or lead. The other kind of pits are large, kind of like waterspots on a car. These typically will polish up pretty well, and the military manuals had an acceptance formula for such pitting. However, dark, pitted barrels are less than desirable. I call a mirror bore with good rifling 'good', and anything less than that 'poor'. I have a 1918 M1911 pistol with a dark, frosty bore that shoots fine. I only shot it on one occasion to verify function, then I cleaned it up and put it away. This is the picture when i got it, and it actually did clean up a little, but this is your basic frosted bore.

[Milsurp Collector]

This is a good thread on the subject of assessing a rifle's bore and it has some great pictures --> Inspecting Rifling

[JimF4M1s (Deceased)]

Those almost look like a James Bond entro, nice pictures.