Counter Bored?

iflylow74 · 07-27-2008, 12:43 AM

Ive seen some ads for mosins that said they are counter bored. What does that mean?

ingous · 07-27-2008, 12:46 AM

If I am not mistaken then either the barrel has been sawed off and re-crowned, or the barrel has been drilled out a bit.

toolman · 07-27-2008, 12:51 AM

This just means that the muzzle-end of the barrel has been bored out a bit using a piloted reamer to remove damaged rifling. This is usually done because the rifling has been damaged by careless use of a cleaning rod.

SwedeSteve · 07-27-2008, 12:56 AM

Counterboring is done to remove bad rifling near the crown of the bore. The rifling has been marred by poor cleaning practices, or eroded (mostly in carbines). This final end of the rifling is critical to accuracy. If it is messed up, then the bad portion of rifling is bored out larger than 7.62mm so that the bullet does not get messed up by bad rifling. If a rifle is counterbored, it needed it. While I believe it does not detract from the rifles value if you will be shooting it, some collectors say otherwise. To test for counterboring. Take a 7.62mm bullet or cartridge and insert it bullet first into the barrel. If the barrel gobbles up the bullet, it is counterbored.

iflylow74 · 07-27-2008, 01:00 AM

So if they are counter bored does that mean the accuracy wont be as good?

SwedeSteve · 07-27-2008, 01:07 AM

No. If it is counterbored a inch it is like cutting an inch off the barrel, basically. Won't effect the Long Rifles, and the carbines don't burn all the powder fast enough in a surplus cartridge anyway. Hence the huge fire-ball.

toolman · 07-27-2008, 01:17 AM

^+1. Counterboring will slightly affect velocity, but not so much that you'd notice unless you have a chronograph.

LefthandShooter · 07-27-2008, 06:26 AM

I thought it was a rifle siting on a countertop with nothing to do (being bored) hence the term "counter bored"?

I know:

toolman · 07-27-2008, 01:12 PM

Quote:

Originally Posted by LefthandShooter

I thought it was a rifle siting on a countertop with nothing to do (being bored) hence the term "counter bored"?

I know:

And:

.......

LefthandShooter · 07-28-2008, 06:02 AM

Quote:

Originally Posted by toolman

And:

.......

Promise?

toolman · 07-28-2008, 08:50 AM

Quote:

Originally Posted by LefthandShooter

Promise?

Nah, we love ya man!

kerriganm49 · 07-29-2008, 12:10 PM

I had to have an inch cut off the barrel of an M91/30 (Finn Capture) and by a gun-smith/machine shop work. This got rid of the bubba job someone had done using the round wood screw and valve grinding compond down about a inch in the barrel (it looked awful!). Shoots great now, tripple stacked front site is now only a half inch from the end of the barrel. Most of the 91/30 I have and have seen, all have had counter- boring done to them, and all the one I have purchased like this all shoot great!

Dan K. Evans · 08-28-2008, 02:07 PM

iflylow74 - I am a great admirer Gen. N.B. Forrest. My great grandfather was recruited by him in western Kentucky, served in a Tennessee regiment, wounded at Brice's Crossroads in Mississippi and surrendered in Alabama at the end of the war. Forgive me for the non-gun post. Dan

Kompressor · 09-16-2008, 02:10 AM

Quote:

Originally Posted by LefthandShooter

I thought it was a rifle siting on a countertop with nothing to do (being bored) hence the term "counter bored"?

I know:

I thought it was some counter measure action from those, like me, who are bored with all the Mosin Nagant posts on this board!
-Or at least haven't yet figured out what it's all about with those MN guns. Somebody, please explain it to me...

BOHICA1962 · 09-16-2008, 11:10 AM

Quote:

Originally Posted by Kompressor

I thought it was some counter measure action from those, like me, who are bored with all the Mosin Nagant posts on this board!
-Or at least haven't yet figured out what it's all about with those MN guns. Somebody, please explain it to me...

Your MNs won't keep you warm through those Three Dog Nights but you need to keep them under the covers.........they have feelings too.

Yogi · 12-13-2008, 09:40 AM

Since my 1942 Izzy 91/30 has been counterbored, that should make it easier to have the muzzle compensated, correct?

abrams437 · 01-01-2009, 02:46 PM

Bohica: Great screen name. I once had a commander that had a tank and a jeep named Big Bohica and Little Bohica.

Mike82 · 01-02-2009, 12:58 AM

counterbored rifles can be modded for better shooting....like taking the counterbored section and angle drilling holes or slots into the 11:00 and 1:00 positions with an almost vertical cut/drill downwards....this causes gasses to release upwards, acting like correcting rockets on a space shuttle, thus reducing muzzle rise.

paynetrain · 01-13-2009, 07:50 PM

My 1936 mosin 91-30 has a counterbore of 2 inches, the bore looks really good, Im hoping it will shoot ok. Im new to G and G and sorry to barge in on you guy's uninvited but about myself, 39 years old Married with 2 son's 11 and 14 , bought them mosins for christmas,1936 and 1939 no counterbores, hope the counterboring thing has no effect on accuracy and life of rifle.On mine that is.

Fitterman24 · 01-13-2009, 10:39 PM

Welcome to G & G. I don't think you will see a difference between it and the other 2 as far as accuracy goes---it may be better than the non counterbored guns---lot of bore variables. They counterbored to remove chewed up rifling/crowns from improper cleaning or accidents to extend the life of the weapon. I would imagine most Mosin "collectors" (Mosinitis sufferers, actually) have a counterbored one in their inventory. Remember to post pics and model info in the 'Mosin roll call' thread. Again, welcome to the sickness.

07-27-2008, 12:43 AM	#1
iflylow74 Registered User Join Date: Sep 2005 Location: Arkansaw Posts: 1,439 Blog Entries: 11	Counter Bored? Ive seen some ads for mosins that said they are counter bored. What does that mean? __________________ Regnant Populi, Nemo me impune lacessit

07-27-2008, 12:46 AM	#2
ingous Senior Member Join Date: Oct 2007 Location: MN Posts: 615	If I am not mistaken then either the barrel has been sawed off and re-crowned, or the barrel has been drilled out a bit. __________________ "We cannot defend freedom abroad by deserting it at home" --Thomas Jefferson

07-27-2008, 12:51 AM	#3
toolman Senior Member Join Date: Apr 2002 Location: abilene,tx Posts: 7,135 Blog Entries: 25	This just means that the muzzle-end of the barrel has been bored out a bit using a piloted reamer to remove damaged rifling. This is usually done because the rifling has been damaged by careless use of a cleaning rod. __________________ cosmoline is an aphrodisiac!

07-27-2008, 12:56 AM	#4
SwedeSteve Suspected Member Join Date: Feb 2007 Location: Anchortown, Alaska Posts: 23,576 Images: 1	Counterboring is done to remove bad rifling near the crown of the bore. The rifling has been marred by poor cleaning practices, or eroded (mostly in carbines). This final end of the rifling is critical to accuracy. If it is messed up, then the bad portion of rifling is bored out larger than 7.62mm so that the bullet does not get messed up by bad rifling. If a rifle is counterbored, it needed it. While I believe it does not detract from the rifles value if you will be shooting it, some collectors say otherwise. To test for counterboring. Take a 7.62mm bullet or cartridge and insert it bullet first into the barrel. If the barrel gobbles up the bullet, it is counterbored. __________________ Thank God we don't get as much Government as we pay for! -Will Rogers

07-27-2008, 01:00 AM	#5
iflylow74 Registered User Join Date: Sep 2005 Location: Arkansaw Posts: 1,439 Blog Entries: 11	So if they are counter bored does that mean the accuracy wont be as good? __________________ Regnant Populi, Nemo me impune lacessit

07-27-2008, 01:07 AM	#6
SwedeSteve Suspected Member Join Date: Feb 2007 Location: Anchortown, Alaska Posts: 23,576 Images: 1	No. If it is counterbored a inch it is like cutting an inch off the barrel, basically. Won't effect the Long Rifles, and the carbines don't burn all the powder fast enough in a surplus cartridge anyway. Hence the huge fire-ball. __________________ Thank God we don't get as much Government as we pay for! -Will Rogers

07-27-2008, 01:17 AM	#7
toolman Senior Member Join Date: Apr 2002 Location: abilene,tx Posts: 7,135 Blog Entries: 25	^+1. Counterboring will slightly affect velocity, but not so much that you'd notice unless you have a chronograph. __________________ cosmoline is an aphrodisiac!

07-27-2008, 06:26 AM	#8
LefthandShooter Got Jesus? Join Date: Nov 2007 Location: Northeastern Ohio Posts: 4,354 Blog Entries: 2	I thought it was a rifle siting on a countertop with nothing to do (being bored) hence the term "counter bored"? I know: __________________ May God give us the wisdom & strength to live our lives in a manner that will be pleasing unto Him.

07-29-2008, 12:10 PM	#12
kerriganm49 Senior Member Join Date: May 2008 Location: Ward, AR Posts: 135	I had to have an inch cut off the barrel of an M91/30 (Finn Capture) and by a gun-smith/machine shop work. This got rid of the bubba job someone had done using the round wood screw and valve grinding compond down about a inch in the barrel (it looked awful!). Shoots great now, tripple stacked front site is now only a half inch from the end of the barrel. Most of the 91/30 I have and have seen, all have had counter- boring done to them, and all the one I have purchased like this all shoot great!

08-28-2008, 02:07 PM	#13
Dan K. Evans Member Join Date: Dec 2007 Location: West Virginia Posts: 76	iflylow74 - I am a great admirer Gen. N.B. Forrest. My great grandfather was recruited by him in western Kentucky, served in a Tennessee regiment, wounded at Brice's Crossroads in Mississippi and surrendered in Alabama at the end of the war. Forgive me for the non-gun post. Dan

12-13-2008, 09:40 AM	#16
Yogi Senior Member Join Date: Nov 2008 Location: Albuquerque Posts: 766	Since my 1942 Izzy 91/30 has been counterbored, that should make it easier to have the muzzle compensated, correct?

01-01-2009, 02:46 PM	#17
abrams437 Member Join Date: Nov 2008 Location: Upstate South Carolina Posts: 18	Bohica: Great screen name. I once had a commander that had a tank and a jeep named Big Bohica and Little Bohica.

01-02-2009, 12:58 AM	#18
Mike82 MMmmm.....I Like PIE!!!!! Join Date: Feb 2008 Location: Starkville, Mississippi USA Go BullDAWGS!!! Posts: 2,735 Images: 7	counterbored rifles can be modded for better shooting....like taking the counterbored section and angle drilling holes or slots into the 11:00 and 1:00 positions with an almost vertical cut/drill downwards....this causes gasses to release upwards, acting like correcting rockets on a space shuttle, thus reducing muzzle rise. __________________ No Trespassing! Violators Will Be Shot! Survivors Will Be Shot Again!

01-13-2009, 07:50 PM	#19
paynetrain Senior Member Join Date: Jan 2009 Location: The Georgia that didnt get attacked by Russia Posts: 865 Images: 2	Counterbored My 1936 mosin 91-30 has a counterbore of 2 inches, the bore looks really good, Im hoping it will shoot ok. Im new to G and G and sorry to barge in on you guy's uninvited but about myself, 39 years old Married with 2 son's 11 and 14 , bought them mosins for christmas,1936 and 1939 no counterbores, hope the counterboring thing has no effect on accuracy and life of rifle.On mine that is.

01-13-2009, 10:39 PM	#20
Fitterman24 Member Join Date: Nov 2008 Location: Missouri KC area Posts: 90	Welcome to G & G. I don't think you will see a difference between it and the other 2 as far as accuracy goes---it may be better than the non counterbored guns---lot of bore variables. They counterbored to remove chewed up rifling/crowns from improper cleaning or accidents to extend the life of the weapon. I would imagine most Mosin "collectors" (Mosinitis sufferers, actually) have a counterbored one in their inventory. Remember to post pics and model info in the 'Mosin roll call' thread. Again, welcome to the sickness.