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Counter Bored?

Discussion in 'Mosin Nagant' started by iflylow74, Jul 27, 2008.

  1. iflylow74

    iflylow74 G&G Enthusiast

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

  2. ingous

    ingous G&G Newbie

    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.
  3. toolman

    toolman Resident Sasquatch Forum Contributor

    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.
    lynxpilot and jwrauch like this.
  4. SwedeSteve

    SwedeSteve Freedom Zealot Forum Contributor

    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.
    jwrauch likes this.
  5. iflylow74

    iflylow74 G&G Enthusiast

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

    SwedeSteve Freedom Zealot Forum Contributor

    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.
    jwrauch likes this.
  7. toolman

    toolman Resident Sasquatch Forum Contributor

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

    LeftHandShooter G&G Evangelist

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

    I know: :hitwithrock:
  9. toolman

    toolman Resident Sasquatch Forum Contributor

    And: :buttkick: :slap: :spank: :twak: .......:p
  10. LeftHandShooter

    LeftHandShooter G&G Evangelist

  11. toolman

    toolman Resident Sasquatch Forum Contributor

    Nah, we love ya man! :D
  12. kerriganm49

    kerriganm49 G&G Newbie

    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!
  13. Dan K. Evans

    Dan K. Evans G&G Newbie

    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
  14. Kompressor

    Kompressor G&G Newbie

    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...
  15. BOHICA1962

    BOHICA1962 G&G Newbie

    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.
    Kad Skirata likes this.
  16. Yogi

    Yogi G&G Newbie

    Since my 1942 Izzy 91/30 has been counterbored, that should make it easier to have the muzzle compensated, correct?
  17. abrams437

    abrams437 G&G Newbie

    Bohica: Great screen name. I once had a commander that had a tank and a jeep named Big Bohica and Little Bohica.
  18. Mike82

    Mike82 G&G Newbie

    counterbored rifles can be modded for better 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. :09:
  19. paynetrain

    paynetrain G&G Newbie


    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.
  20. Fitterman24

    Fitterman24 G&G Newbie

    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.
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