RotoMetals2Titan ReloadingLee PrecisionRepackbox
Reloading EverythingWidenersMidSouth Shooters SupplyInline Fabrication
Load Data
Results 1 to 11 of 11

Thread: Help with counter boring

  1. #1
    Boolit Bub
    Join Date
    Sep 2016
    Posts
    72

    Help with counter boring

    I have a 1903 Springfield with a 1943 barrel, and I shoot cast bullets. Can anyone help me with proper counter boring techniques? I hope that will help a bit with accuracy without re-barreling.
    Thanks Nick

  2. #2
    Boolit Grand Master pietro's Avatar
    Join Date
    Mar 2008
    Location
    New England
    Posts
    5,252
    .

    AFAIK, you'll need a piloted drill bit that's at least 5/16" in diameter - but I would first re-crown the muzzle to determine if you need to go as far as counterboring.

    Bubba would just hog out the bore with a power hand drill, but in any counterbore, the new/interior muzzle (end of the rifling) would also need re-crowning.

    .
    Now I lay me down to sleep
    A gun beside me is what I keep
    If I awake, and you're inside
    The coroner's van is your next ride

  3. #3
    Boolit Bub
    Join Date
    Sep 2016
    Posts
    72
    Damage from cleaning rods opened the muzzle to 32 cal and is somewhat elliptical. It goes down about an inch.
    Oh by the way what is AFAIK?

  4. #4
    Boolit Master

    Join Date
    Mar 2010
    Location
    NC Arkansas
    Posts
    1,394
    Quote Originally Posted by fiatdad View Post
    Damage from cleaning rods opened the muzzle to 32 cal and is somewhat elliptical. It goes down about an inch.
    Oh by the way what is AFAIK?
    As Far As I Know
    Spell check doesn't work in Chrome, so if something is spelled wrong, it's just a typo that I missed.

  5. #5
    Boolit Grand Master

    Join Date
    Mar 2013
    Location
    Northwest Ohio
    Posts
    14,455
    Depending on the machines you have available a piloted drill or counter bore will do. If a lathe is available then it can be set up indicated in and a small boring bar used.

    I would recommend plugging the bore with a couple patches below the depth of cut to keep chips contained, use lots of good oil, a slow feed and speed.

    What might do good is a tapered pin reamer ( #7 was used to modify m 14 / m1a flash hiders) this would give a funnel shape counter bore. A hand reamer could be used with a tap wrench by hand

  6. #6
    Boolit Master
    Join Date
    Jan 2010
    Location
    South Louisiana
    Posts
    633
    Lets back up, attacking the barrel and counterboring with a hand drill right off the bat is not the way to go.
    First, are you having accuracy issues or bullets keyholing?
    First, have you slugged the barrel on both ends? are you sizing properly at .001 over bore diameter? is the muzzle larger than the breach end? by how much? if it is, how far into the bore before you get to a consistent size? do you think a simple re crown would help? maybe a cut back and re crown?
    I just dont think that using hand tools and a piloted counterbore is going to work well. ONe you need a tight fitting pilot, lots of oil/air blast/ and frankly running one of those by hand is gonna wear you out.
    I think you'd be money ahead to have it rebarreled with a critereon barrel.
    NRA High Master XTC
    DR# 2125

  7. #7
    Boolit Master Tokarev's Avatar
    Join Date
    Aug 2007
    Location
    Canada (North of upstate NY)
    Posts
    945
    Quote Originally Posted by fiatdad View Post
    Damage from cleaning rods opened the muzzle to 32 cal and is somewhat elliptical. It goes down about an inch.
    Oh by the way what is AFAIK?
    I agree with akajun and am concerned about the bold part:

    somewhat elliptical

    Even if you bought a proper counterbore and made a proper pilot, the elliptical shape would still throw the tool off. It has to be done on a lathe.

  8. #8
    Boolit Master

    Join Date
    Mar 2010
    Location
    NC Arkansas
    Posts
    1,394
    As Far As I Know
    Spell check doesn't work in Chrome, so if something is spelled wrong, it's just a typo that I missed.

  9. #9
    Boolit Grand Master Outpost75's Avatar
    Join Date
    May 2013
    Location
    over the hill, out in the woods and far away
    Posts
    10,158
    If you have a .30-'06 or .308 Win. Chambering reamer with rotating, removable pilot, just select pilot to fit and run the chambering reamer into the muzzle and stop when the shoulder cone cleans up the crown edges.
    The ENEMY is listening.
    HE wants to know what YOU know.
    Keep it to yourself.

  10. #10
    Boolit Master

    Join Date
    Feb 2007
    Location
    Lewiston, Idaho
    Posts
    2,732
    What Outpost75 said. You want a pilot that will rotate, otherwise you can mess up the rifling real fast. Any 30 cal chamber reamer would work, even a 30-30. Also you need a lathe to keep thing running strait. With a lathe a small boring bar could be used. I don't recommend re-lining the bore on a 30-06 unless you can come up with a liner made from 4140 steel, most are made from 4130 which is great for lower pressure rounds.
    Maybe check this out.
    Last edited by Red River Rick; 11-21-2021 at 12:20 PM. Reason: Ebay links are not allowed

  11. #11
    Boolit Master
    Join Date
    Nov 2017
    Location
    brisbane ,qld,australia
    Posts
    2,125
    One thing most dont consider is how deep should a counterbore be?........I use the boring bar method,and consider the cut deep enough when I can see a clearly defined bore and grooves .....i have always used a flat cut for muzzles ,not pretty like a crown ,but the flat can be off centre ,and there is no ill effect.......if you have a conical crown ,it must be exactly centred on the bore.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check