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View Full Version : Where the heck are all the muzzle crowning tools??


Daekar
May 16, 2011, 10:26 PM
I've been trying for literally months now to get ahold of a crowning tool for use on SKS and Mosin-Nagant rifles. If you don't want to spend $150+ you're up a creek, because everybody is sold out completely! I've tried google, brownells, and midway... I'm not sure what else to do. It's held up several projects just trying to get this one tool at a reasonable price. Does anybody know where I could get an 11 or 45 degree crown with 7.62/30 cal brass pilot?

Ah, I actually found one... it was just labelled a 79 degree tool...

GURU1911
May 17, 2011, 05:41 AM
The 79 / 11 degree tools are the same: 90 degrees minus 11 equals 79 degrees !!!!!! Ta-dahhhhhh.

For those calibers you will need a .308" pilot. I prefer the steel version.

Check again with brownell's regarding the crowning tool. If they are out-of-stock, i was not aware of this.

Guru1911

GURU1911
May 17, 2011, 06:43 AM
As a favor to you, i checked stock @ brownell's. The 45 & 79 degree crowning tools & pilots for .308 caliber rifles are in-stock. The rest is up to you.

You owe me one, kuz !!!!

Guru1911

Scorch
May 17, 2011, 11:11 AM
Any gunsmith worthy of the title has a crowning tool sitting in the corner. It's called a lathe.

Rifleman1776
May 17, 2011, 01:34 PM
Chuck up a brass round-head screw in your hand drill. Apply an abrasive paste and work on that bore. Cost? Pennies.
Tip courtesy of Brownell's Gunsmith Kinks books.

FrankenMauser
May 17, 2011, 04:05 PM
Chuck up a brass round-head screw in your hand drill. Apply an abrasive paste and work on that bore. Cost? Pennies.
Tip courtesy of Brownell's Gunsmith Kinks books.

My grandfather recrowned a Type 99 Arisaka with that method (except he had solid brass balls that he chucked directly in his drill press).

It worked amazingly well. ...and they're self-centering. ;) (so long as your screw has no run-out, and/or the ball is actually round)

Unclenick
May 17, 2011, 05:41 PM
Actually, your grandfather did the right thing. I looked at round head bolts with a circle template one time and found they were mostly elliptical, so they have to go straight in or you can get an asymmetrical crown.

I've had great success using ball bearings I groove with a Dremel tool and superglue to a piece of tubing for a handle. I have a lathe, but this lets me use it just to cut off the muzzle square and dress the OD, which doesn't require indicating out a perfect bore center. The lap then takes about 10 minutes and gets a sharper result.

I wrote it up long ago, including how to pick the ball size to get a certain angle at the edge of the grooves. I've attached it in PDF format.

http://thefiringline.com/forums/attachment.php?attachmentid=65182&d=1292014695

RedNeckWino
May 19, 2011, 12:00 PM
Unclenick:
Great post. Thanks for sharing.

triggerman770
May 27, 2011, 09:53 AM
" for use on SKS and Mosin-Nagant rifles"
actually you will need a 311 pilot
080-943-311 which is in stock now

dfaugh
May 27, 2011, 09:58 AM
You need a .311 pilot, NOT a .308...Speaking from experience w/ both SKS and Mosin rifles.

a7mmnut
May 27, 2011, 10:17 AM
???:confused: I've always had them turned in a lathe. It takes a few minutes to grind in a new cutter and indicate for runout, but then it's a breeze. In addition, you can alter the compound tool holder to use various cuts and angles.

-7-

FrankenMauser
May 27, 2011, 01:44 PM
Very few people own lathes, or have access to them.


Larry Potterfield
Recrowning by hand:
http://www.youtube.com/watch?v=b43odFm0mrI

Brass screw in a drill:
http://www.youtube.com/watch?v=OorpZlG28fI&feature=related

Crown repair tool in a drill, and with a lathe:
http://www.youtube.com/user/MidwayUSA#p/search/7/x3ELBpqYCQc

BobGee
September 18, 2012, 09:51 AM
Hi Unclenick, Thanks for the advice in your attachment (Crown Ball Lapping2.PDF). I shall be re-crowning my Walther GPS-C barrel using it this weekend.

However, although this post is old, for the sake of posterity I think I should mention that the formula for choosing the lapping ball size is incorrect. The diameter (phi) should be: D/sin"theta", not 2D/sin"theta".

Thanks again for the info.

Unclenick
September 18, 2012, 10:11 PM
Bob,

Welcome to the forum.

I Actually put 2D/sinĪ˜ in an earlier version of the PDF file. It was pointed out to me I was thinking in radius instead of diameter.

Edit:

OK. Now I see the problem. See next post below. The copy of the file in this post is the old one. The correct one is in another post on the forum. I taken out the bad copy and put a link to the correct one in.

jpmche
September 21, 2012, 07:07 AM
So, the correct equation is D/sin(theta). Right?

Sent from my SCH-I510 using Tapatalk 2

Unclenick
September 21, 2012, 11:24 AM
Now I see the problem. The copy of the file in this thread is the old one. The correct one is in another post on the forum. I've taken out the bad copy and put a link to the correct one in the other post.

jpmche
September 21, 2012, 11:29 AM
Thank you, sir!

Sent from my SCH-I510 using Tapatalk 2

tobnpr
September 23, 2012, 10:20 AM
Brownells 79 degree cutter, .311 pilot (NOT .308...) yielded this:

http://i211.photobucket.com/albums/bb294/tobnpr/IMAG0580.jpg