Muzzle erosion

[Trimman]

thoughts on counterboreing vs crowning a muzzle.

[Orlando]

Does rifle shoot poorly?
What does muzzle measure?

[Trimman]

Shoots ok. Checked a bullet in my bolt action rifle,,, bullet goes in muzzle of M1 about .10" deeper.

[TJT]

I have a Sept '42 SA that had mw of about 3 (I checked it with machinist's gage pins). I had it c-bored to a depth of .190" to get rid of the belling at the muzzle. It now has a mw of 0. Before the c-bore it would only hold the 7-8 rings at 100 yds on an SR1 target. After the c-boring, it will now clean an SR1 target at 100 yds. Best $50 I ever spent on an M1 rifle. I also use gage pins to check mw instead of a mw gage, but that's a story for another time.
Jon
ps--a simple re-crown may or may not help you any. I know in MY case it would've been an exercise in futility. A simple re-crown usually won't help unless the belling is at the very end and doesn't exceed more than .025" in depth.

[Trimman]

Sounds like a plan. I thought the same about a c-bore. Doesn't change the looks and has to shoot better.

[TJT]

Trimman,
Just don't let the purist's know that you c-b'd the bore, otherwise they'll want to tar and feather you and then crucify you. Ask me why I know this.
Jon
I'll try to get a pic up in the next couple of days.

[David Milisock]

Sounds like a plan. I thought the same about a c-bore. Doesn't change the looks and has to shoot better.

Let us know how it works out for you please.

[TJT]

Pics as promised. Notice how the rifling ends cleanly 3/16" from the end of the muzzle. Notice too, although the barrel needs cleaning (shame on me), the c-bore itself is clean as a whistle. The rifle still functions perfectly. The mw is effectively a "0".
Jon

[Trimman]

Was this c-bore done with a hand Reamer or a lathe?
where did you get the tool?

[TJT]

It was done on a lathe with a 4-jaw independant chuck and a steady rest. The cb was cut, not reamed. The only reason I didn't do it myself is because with the set up required, it would have cost me more in time than it did to pay the local 'smith $50 to do it for me. And besides, the 4 jaw chuck/lathe at work is always busy with no time to spare.

Jon

[Trimman]

A .303 gage pin went down the bore about 5/8".
Think maybe a very well shot out barrel.

[Trimman]

Correction, 1/4" down barrel.

[TJT]

My c-bore is 3/16" deep. You'll be fine with a 1/4" deep c-bore. You can c-bore almost to the gas hole and it will work fine. What size pin goes thru the bore? How far in does the next size up pin go? That's the depth you need to go to.
Jon

[Trimman]

Using a bore gage,, it went in to the .3025 mark.

[TJT]

Ditch the mw gage. Get pin gages. What size goes ALL the way thru the bore? What is the smallest size that DOES NOT go thru? How far does THAT pin go into the bore? THAT'S how deep the c-bore needs to be.
Jon