Can someone please explain "counterboring" to me?

Discussion in 'The Powder Keg' started by Cyrano, Jan 6, 2008.

  1. Cyrano

    Cyrano Resident Curmudgeon Forum Contributor

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    If I'm not mistaken, the idea is to fix a rifle whose muzzle has somehow been damaged, without rebarreling the action; a governmental economy measure. Yes?

    I think what I want to know is two things.

    First, does counterboring appreciably affect the accuracy of the weapon? If so, which way?

    Second, is a counterbored rifle more or less valuable (and more or less pricey) than one that is not counterbored?

    I'm thinking about adding a Mosin M38 to my inventory (I can't really call it a collection yet), and it seems like all the ones I see in online stores or on auction sites are counterbored. Can any of the Mosin shooters here advise me if a counterbored rifle is a good shooter and a good choice?
  2. marion57

    marion57 G&G Newbie

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    counter bored rifles are or can be good shooters .. the way it was explained to me was most of the M38s mussles were damaged by the cleaning rod and constent cleaning .. Yes its a quick way to restore the function od a rifle by drilling(counter boring) the mussle till the rifle has good rifling down to the counter bore!!I dont have one that is counter bored so cant speak to the accuracy !! My understanding is there as good as any other rifle ..
  3. M39SKY

    M39SKY G&G Newbie

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    The only reason for counterboring is to improve accuracy of a rifle with good barrel but worn or damaged crown. My guess, is that the military don't want to alter the length of the barrel (uniformity and bayonet attachment issue?) so they counterbore as a way of recrowning.
    If the only thing needing improvement is the crown, then yes it will appreciably increase accuracy of the rifle.
    A rifle with counterbored barrel is less valuable than a similar rifle which is not counterbored given the same accuracy, in my opinion. Is it a good choice? Depends on the price and other choices available to you. Would it make a good shooter? It pretty much have new crown, so it can be. I do have a Mauser that is counterbored and shoots all over the place. Damaged counterbored crown? Maybe. Another issue with counterbored barrels is that should I need to recrown them I would need to cut the barrel more to remove the counterbore. I cannot counterbore.
    There are some m38s that are not counterbored showing up on auctions from time to time. Or you might consider 91/59 or M44.
  4. Cyrano

    Cyrano Resident Curmudgeon Forum Contributor

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    I've thought about a 91/30, but they are a little long for my taste. The M38 is right about the length I like in something I'd conceivably take out after deer, though given the state of my eyes I think I'd need to put a scope on it; and given I'd need to replace the straight bolt with a bent bolt to do that, it's in a price range I'm willing to pay for when you add that additional cost in.
  5. MosinGirl

    MosinGirl G&G Newbie

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    My M38 has been counterbored and it shoots just as good as the others that aren't counterbored. And you don't really have to get a turned down bolt to put a scope on a Mosin. My M44 has a scope and it still uses it's original bolt. Just had to remove the rear sight.
    [​IMG]


    Manda in Kent
  6. SwedeSteve

    SwedeSteve Freedom Zealot Forum Contributor

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    Counterboring removes damaged rifling. So effectively, it is shortening the barrel. Should not change overall accuracy if done correctly. Since it is done to clean up BAD rifling, on a bore that needs it, I do not think it hurts it's value on most Mosins.
  7. NRAJOE

    NRAJOE YOU TALKIN' TO ME!? Forum Contributor

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    Ivan wasn't too careful with their cleaning rods or dropping their Nagants.

    Counterbored is fine...

    I actually have a 91/30 and a postwar M44 that was not counterbored....
  8. Ricochet

    Ricochet G&G Newbie

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    Most were counterbored in the refurbishing process whether they needed it or not. It's not an issue for resale value, the collectors aren't going to give big bucks for these refurbished rifles, anyway.
  9. just_a_car

    just_a_car G&G Newbie

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    I guess I've been lucky... my 91/30 ex-sniper and my two 91/59's are not only not counterbored, but also numbers-matching. *glee!*

    It seems that Big 5 gets a lot of non-counterbored mosins in the WA State area. I have yet to see one and I've looked at quite a few.
  10. NRAJOE

    NRAJOE YOU TALKIN' TO ME!? Forum Contributor

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    All I collect is stamped number matching...no line outs...no electropencil...
  11. Ricochet

    Ricochet G&G Newbie

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    And even the ones as NRAJoe describes, if they came in the batches that have been imported in the last few years, are not "original" rifles. They were put together in the armories from parts of various salvaged rifles, with some new parts where necessary, and numbers on bolts, buttplates, floorplates, etc. were ground away and restamped to match the barrel number. There are few exceptions to that, and no sure way to tell. It's typical to see things like late WWII type stocks on '30s rifles with all numbers matching. That's just the way it is and is fine with me, but the "serious collectors" are turning up their noses. Which is why they're so affordable to folks like me!
    :approve:
  12. marion57

    marion57 G&G Newbie

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    my ex drgoon 1927 floor plate is lines out and retamped ! it isnt unusual and you can buy a new floor plate with no stamp if you want LOL ,it in no way detracts from the rifle and as stated I wouldnt turn up my nose at a reburbished rifle :)
  13. lowercase

    lowercase G&G Newbie

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    How can you tell if your gun has been counterbored?
  14. marion57

    marion57 G&G Newbie

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    Stick a bullet in the end of it and if it swallows the bullet and casing its counter bored.. If not it should show all; the casing and about a 1/8 to 2/8 of the bullet sticking out of muzzle
  15. gandog56

    gandog56 G&G Enthusiast

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    Just checked my 91/30. Not counter bored.
  16. lowercase

    lowercase G&G Newbie

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    I tried the bullet test with both of mine and neither seems to be conter bored. Both rifles look great, too. The only thing I've found so far is that my 1943 Tula has a very difficult to work bolt. I hope that goes away after a good cleaning.

    Now here's a dumb question: Since the bullet (not the casing) will only partially fit into the muzzle of the rifle, how does it get down the barrel when fired?
  17. marion57

    marion57 G&G Newbie

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    Lowercase take that bolt apart and clean it with carb cleaner then oil it good ..you will be amazed !! the bullet is suppose to be a very tight fit so the power of the explosion when fired forces the bullet to go down the barrel and turn with the rifleing.. I probably didnt explain that as well as other but is as good as I can.. do you shop at big 5 lower case?
  18. SwedeSteve

    SwedeSteve Freedom Zealot Forum Contributor

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    I usually carry a straightened paperclip with me, and I can slide it down the barrel and feel for the counterbore.
    I think we have seen the end of "original" non counterbored Mosins tha came across the pond that way. Most are parts-built. Heck, all the M39's started that way That's what cracks me up when people say don't modify your original Mosin (LOL)!
    A few of you know that I started buying "Parts Only" or "As Is" Mosins and trying to bring them back to as correct as possible shooters. If you have any spare-spareparts you wish to trade PM me!
  19. lowercase

    lowercase G&G Newbie

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    Thanks for the advice about the carb cleaner. I'm still waiting for warm weather so I can "sweat" the cosmo out of my guns. I plan to put them out on my back deck wrapped in a black plastic bag. I'll definitely use the carb cleaner when I take the gun apart to clean the metal parts.

    I do go to Big 5 regularly because there is one very close to my house, and that it is an easy place to go look for Mosins.
  20. just_a_car

    just_a_car G&G Newbie

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    I check their adverts every week... even though I know I'm not going to buy a Mosin, I like to know when they're on sale to tease myself. I think it's a symptom of my Mosinitis.

    What part of the PacNW are you from?
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