What is a "counterbored" rifle?


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SteelyDan
April 14, 2004, 01:47 AM
Okay, I'm once again acknowledging my seemingly endless ignorance and asking a simple question: What is a "counterbored" rifle? I've come across the term several times in the last week, probably in connection with C&R rifles, but I've no idea what it means. I gather from the context that it is a bad or less desirable thing, but beyond that...... no idea.

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Houndawg
April 14, 2004, 03:23 AM
A counterbore is when the rifling and part of the inner diameter of the bore is drilled out from the muzzle back far enough to get rid of boogered up rifling. The need for counterboring is caused by poor cleaning methods, ie: not using a rod guide. A counterbore creates a new crown, albeit inside the barrel, and allows the bullet to make a clean exit without being thrown off by damaged rifling.

Many people don't want a counterbored barrel, but I'd rather have a counterbore than a useless barrel.

Counterboring was a common practice with the Russians and a few other European type countries.

SteelyDan
April 14, 2004, 03:41 AM
Thanks 'dawg. So is the idea that if you start out with a 20" barrel, but you've used your muzzle to dig fence posts (or whatever), you can drill an oversized bore into the muzzle and effectively end up with, say, a 19" barrel with sort of an extra 1" of "ported" barrel without the ports??

Houndawg
April 14, 2004, 04:03 AM
Exactly.

Houndawg
April 14, 2004, 04:07 AM
One reason it was common with the Ruskies was the way the bayonet mounted on their rifles. The bayo actually depends on the length of barrel in front of the front sight. They coundn't just lop off the tip of the barrel to get to clean rifling, so they had to go from the inside.

BigG
April 14, 2004, 09:26 AM
You mean it's *gasp* an evil flashhider, so to speak? Oooh think I'm gonna be sick! :uhoh:

JohnBT
April 14, 2004, 09:41 AM
I think they should all be counterbored to protect the crown, but I guess it costs too much in this age of pennypinching corporate types. I was pleased to see that Cooper uses a counterbore.

JT

armoredman
April 14, 2004, 02:28 PM
My M38 Mosin-Nagant is counterbored about 1 inch, but trust me - it does NOTHING to hide the flash! I have good accuracy, so I gather the Russkies were pretty good at this....

Chipperman
April 14, 2004, 06:01 PM
Is the end of the barrel that is counterbored usually left smooth, or does it have any sort of grooving pattern?

MeekandMild
April 14, 2004, 11:16 PM
T/C Omega has an interesting counterbore. It is counterbored about the length of a bullet, but the very end of the barrel is a little bit less counterbored so you end up with an abrasion resistant ring of steel. Which is a good idea because they have steel ramrods.

Houndawg
April 15, 2004, 02:04 AM
Chipperman,

The end of the barrel is usually smooth. It wouldn't matter anyway since the bullet will never touch that portion of the barrel.

Vern Humphrey
April 15, 2004, 02:05 AM
Quote:
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Is the end of the barrel that is counterbored usually left smooth, or does it have any sort of grooving pattern?
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Counterboring removes the "boogered up" rifling, and leaves the last inch or so of the bore larger than before. There would be no point in rifling that section, since the bullet never touches it.

Mk VII
April 15, 2004, 05:04 PM
some years ago a large batch of '03s were imported here and practically all of them were counterbored, even the new WW2 barrels

Chipperman
April 15, 2004, 06:21 PM
"There would be no point in rifling that section, since the bullet never touches it."
I knew that; I was just wondering about the machining of it, and how smooth they made the surface. The bullet is not going to suddenly expand when it reaches the counterbored section. ;)

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