CMP Forums

CMP Forums (http://forums.thecmp.org/index.php)
-   M1 Carbine (http://forums.thecmp.org/forumdisplay.php?f=6)
-   -   How To Evaluate Bore Condition (http://forums.thecmp.org/showthread.php?t=42041)

jmiles1960 04-09-2011 08:49 AM

How To Evaluate Bore Condition
 
Newbie question, but here goes: I've got Winchester M1 1,2xx,xxx that's been through the arsenal a few times. Before I put too much $ into restoring it, I wanted to understand the condition of the bore (barrel). It's clean, shiney from what I see with a light, I can see the grooves (rifling), but what does that really tell me? I'm sure there is a correct way to measure and would appreciate advice on how to assess the condition, etc... barrel has "W" stamp on top, so I'm guessing it is original.

I have heard of muzzle wear gauges, etc... but no little about them or sources.

* * Rifle is an M1 Carbine w/Winchester receiver and barrel * *

Thanks!

steelap 04-09-2011 09:05 AM

Quote:

Originally Posted by jmiles1960 (Post 323341)
Newbie question, but here goes: I've got Winchester M1 1,2xx,xxx that's been through the arsenal a few times. Before I put too much $ into restoring it, I wanted to understand the condition of the bore (barrel). It's clean, shiney from what I see with a light, I can see the grooves (rifling), but what does that really tell me? I'm sure there is a correct way to measure and would appreciate advice on how to assess the condition, etc... barrel has "W" stamp on top, so I'm guessing it is original.

I have heard of muzzle wear gauges, etc... but no little about them or sources.

Thanks!

From the last comment "barrel has "W" stamp on top", I'm assuming that the M1 referenced is a M1 Carbine, not a M1 Garand?

If so, the muzzle wear (MW) at the muzzle end can be measured using a caliber .30 muzzle gauge. Some people use a M2 (30-06) bullet, but to me that is too subjective. The MW will give you some idea of how well the rifle might shoot, although it is only one of many factors.

If the weapon is a M1 Garand, then a throat erosion (TE) gauge could be used to get an estimate of how much of the life of the barrel at the chamber end has been fired away. Under TE=5 is, I think, generally considered to be acceptable for a casual shooter.

To the best of my knowledge there is no M1 Carbine TE gauge. If someone knows of one, I'd love to buy one.

A muzzle gauge or a M1 Garand/30-06 bolt gun TE gauge can be purchased from many sources - CMP, Scott Duff, Brownell's, Midway, etc.

Suggestion - go to the CMP estore or Scott Duff's sight and get a book called The M1 Garand: Owner's Guide - Disassembly, assembly, inspection, repair, cleaning, zeroing, and more.

"Life is Good!"

aka108 04-09-2011 09:08 AM

I'm not well schooled in this area either. I have faith that the Garand's I've recived from CMP have accurate TE and MW readings. When the bore is cleaned and you can see the rifling is strong I believe then that the bore is OK. If it then shoots well and gives decent group sizes then I'm more than satisfied that the barrel is good. I've had several bolt action milsurp Mausers that had dark bores with some pitting. Some were still very accurate and some were basket cases that gave 12 inch groupings at 100 yds.

petro 04-09-2011 09:34 AM

You can make a "poor man's" Muzzle Wear gauge out of a single round of USGI M2 ball .30-06 ammo stuck point first into the muzzle. Just measure how much copper jacket shows when you do this:
5/16"=new,
1/4"=excellent,
1/8"=adequate for plinking,
0=consider a new barrel.



E-7Ret. 04-09-2011 09:35 AM

There's alot more to Barrel-Condition than checking for grooves.
Throat-Erosion- Checked with a throat-Erosion gauge, the TE can tell you approximately how many rounds have been through the barrel by assuming an original TE of 1.5 and figuring 1000 rounds per whole number. For example; a TE of five would indicate approx. 3500 to 4000 rounds fired. Again, this is an approximation as you don't know what the original TE actually was. But it tells you things about the barrel. 1.) It's almost halfway through it's life(10,000 rounds) and, 2.) While it will shoot good recreationally, with a TE that high, as it heats up in a match, it may start blowing up groups. Yes, once TE reaches a certain point it can affect accuracy.
Muzzle-Erosion- Checked with, you guessed it, a Muzzle-Erosion gauge, this is a measure of how accurate the rifle may actually be. All else equal, a good muzzle(3 or Below) can be expected to shoot decent groups. A high ME usually means shotgun patterns instead of groups.
Nicks/dents,etc in the crown- Any of these in the actual crown will cause fliers. As the bullet leaves the muzzle, gas escapes all around it. For good accuracy that gas has to escape equally around the heel of the bullet. All it takes is a small nick or dent to allow more gas to escape at that point and move the heel as it leaves. Result; a Flier.

Barrel Port diameter- Another biggie! Take a #47 drillbit, clean the hole gently with the tip, then turn it around and slide it in. It should go. Next, try to insert a #45 drillbit. If it goes in it fails, port's too big. This means a new barrel. Port-size is important to consistant operation of the gas-system and that's important to accuracy.

Barrel-pads/spline-slots- If your barrel is original it won't have chrome-plated pads. You need to check for corrosion on the pads. If there's alot the Gas-Cylinder probably won't seal properly, consistant operation of the Gas-System can be compromized. The spline-slots should be straight and sharp-edged.

Muzzle and chamber-threads- The threads at both ends need to be clean, not rusty and the muzzle threads sharp and distinct.
Also, the bevel cut for the Locking nut should be clearly-defined.

Rifling, should be shiney and distinct along the bore, no large pits or rings that bulge out the exterior of the barrel. some erosion will exist at both ends unless it's a new barrel.

rcolarco 04-09-2011 09:37 AM

Easiest way to check condition of the bore: shoot the rifle.

Oldloader 04-09-2011 10:15 AM

Quote:

Originally Posted by rcolarco (Post 323359)
Easiest way to check condition of the bore: shoot the rifle.

Hey now! don't start injecting reality logic in here and get everyone confused.

fafenman 04-09-2011 01:24 PM

You can slug the barrel also.
http://www.surplusrifle.com/reloading/slug/index.asp

jmiles1960 04-09-2011 01:25 PM

* * Results - Well, I did the test with the 30-06 M2 round depth in the barrel as described here. The results don't look good. About an 1/8 of inch showing of the bullet to the casing edge. I compared to my NPM M1 Carbine which has 1/4 of inch showing using this test and shoots fantastic at 100 yards.

The Winchester barrel, IMO needs replacing. I'm glad I learned this now, rather than later.

How likely am I to find a new Winchester barrel or what is the recommendation to find a replacement?

Thanks for the help with this.

Jim

The Original Youngblood 04-09-2011 02:44 PM

One of the most useful little tricks that I employ in evaluating bore surface condition requires a new, appropriately-sized, phosphor-bronze bore brush.

As you slowly push the brush thru the bore, you can both hear & feel any roughness that exists.


All times are GMT -5. The time now is 05:50 PM.