Go Back   CMP Forums > CMP Sales > M1 Carbine
Register FAQ Members List Calendar Mark Forums Read

Reply
 
Thread Tools Display Modes
  #1  
Old 05-17-2020, 05:47 PM
RattleOK RattleOK is offline
 
Join Date: Oct 2009
Location: Idaho
Posts: 148
Default MW on counter-bored carbine

Just wondering what is the acceptable way to express muzzle wear readings on a counter-bored carbine. I purchased from CMP, a barreled receiver, Bavarian rock-ola, that had an arsenal counterbore done. It is very easy to see and measure how deep the new larger bore goes into the barrel...only 1.5 deep according to my gauge. Total muzzle wear
reading is 3.25;

So, is it that easy? 3.25 -1.5 = mw of 1.75?
-or-
mw is still 3.25, regardless of any counter-bore?

Don't usually hear much on counter-bored carbines, and just wondering what others opinions are.?
I've gathered the parts it's now time to build this puppy.

Last edited by RattleOK; 05-17-2020 at 05:52 PM.
Reply With Quote
  #2  
Old 05-17-2020, 05:57 PM
meplat meplat is offline
 
Join Date: Jan 2010
Location: Prescott, AZ
Posts: 3,864
Default

Subtract and divide by two. Kidding.

You would measure just as you would if you used your gage on a "normal" bore, except you have to determine where the point of contact of the lands are on your gage. Which you obviously can't do since you can't see the contact below the end of the barrel. Or is it obvious?

So ...

Smear your gage with some lipstick, stick in your bore. When you pull it out, you'll see the contact ring. That indicates the bore diameter on your gage, as usual.

Could sharpie your gage and "spin it around" in the muzzle to mark but some might consider that abusive.

HTH


Last edited by meplat; 05-17-2020 at 06:00 PM.
Reply With Quote
  #3  
Old 05-17-2020, 06:39 PM
RattleOK RattleOK is offline
 
Join Date: Oct 2009
Location: Idaho
Posts: 148
Smile

Lol...I tried it first using the Pythagorean theorem to no avail...ha!

Yes, I would guess that those lands extend all the way out to pretty much where the counterbore ends, so that 1.75 muzzle wear is close to accurate. Will try your "smudge" test to be sure of contact point. Thanks
Reply With Quote
  #4  
Old 05-17-2020, 08:25 PM
6 Ring 6 Ring is online now
 
Join Date: Apr 2010
Location: South of Atlanta, Ga
Posts: 3,273
Default

Easy, measure the depth of counter bore. Insert MW gauge. Mark the muzzle reading. Remove the gauge and measure down the depth measurement earlier and that is the gauge reading.
Reply With Quote
  #5  
Old 05-17-2020, 11:11 PM
RattleOK RattleOK is offline
 
Join Date: Oct 2009
Location: Idaho
Posts: 148
Default

Thanks, yes, that jives with my numbers:
Counter bore depth(1.5), subtracted from gauge reading at muzzle(3.25). Confident MW is now 1.75

Just kinda strange that any mw gauge will show mw of 3+ for this barrel, yet, because of the counter-bore, is now only 1.75!
Reply With Quote
  #6  
Old 05-18-2020, 07:59 AM
03man 03man is offline
 
Join Date: Feb 2015
Location: near Charlotte NC
Posts: 7
Default

Not strange at all, IMO.
The muzzle is now larger in diameter and smooth bore.
The rifling is not at the muzzle any longer.
Reply With Quote
  #7  
Old 05-18-2020, 11:34 AM
imarangemaster imarangemaster is offline
 
Join Date: Oct 2009
Location: Northern California
Posts: 571
Default

LOL! At least yours is counter boared! About 10 years ago I picked up a transitional Inland (1944 with adjustable rear sight and Type II Band) on gunbroker that swalloed the ME gauge and it was not counter bored! At 25 yards the group was the size of a coffee saucer. It was described as "MUZZLE SHOWS SOME WEAR" in the auction!
Reply With Quote
  #8  
Old 05-18-2020, 12:13 PM
RattleOK RattleOK is offline
 
Join Date: Oct 2009
Location: Idaho
Posts: 148
Default

Ha, That brings "buyer beware" to a whole new level! I bring my muzzle wear gauge to gun shows just in case. That gauge is a little less than 3 inches long. More than once, a gun show carbine swallowed it all but the knurled finger grip on the end. yep showed a little wear all right.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



All times are GMT -5. The time now is 07:54 PM.