Help with counter boring

[fiatdad]

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

[pietro]

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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.

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[fiatdad]

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?

[ulav8r]

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

[country gent]

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

[akajun]

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.

[Tokarev]

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.

[ulav8r]

As Far As I Know

[Outpost75]

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.

[John Taylor]

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.

[john.k]

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.