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Posted: 6/19/2003 8:55:27 PM EDT
Is it alright to re-cut the crown on the muzzle of a chrome lined barrel. I noticed that the chrome does come out just past the muzzle and was wondering if it might cause any problems with the chrome lining or anything else cutting it to an 11 degree target type crown.
Link Posted: 6/20/2003 3:08:17 PM EDT
Silverback, I've read on this site that cutting/crowning a chrome lined barrel can cause the chrome to flake, but I've never seen it happen myself. I've cut and crowned a half dozen or so COLT barrels and had no bad results either with poor accuracy or flaking. Only one of the barrels has been shot extensively, so the jury may still be out, but at this point my thought is that I'm not afraid to do it on a COLT barrel. As far as other brands, I don't know what results you might get.
Link Posted: 6/22/2003 2:59:17 AM EDT
Never cut an AR barrel, but have cut several SKS jobs over the years w/o any problem whatsoever. Also recrowned a commercial hard chromed M1 Carbine barrel some years back w/no ill effects. Can't imagine that a proper recrown on an AR barrel would be a problem [:D]
Link Posted: 6/22/2003 3:46:17 AM EDT
I've had trouble cutting the crown on a chrome lined FAL barrel. The trouble seems to be that the chrome is so hard that no matter what presure i use i get chatter. It still came out fine and is a good shooter but i'll probably use the booger picking method next time with a marble and valve lapping compound rather than put wear and tear on my crown cutters.
Link Posted: 6/22/2003 4:47:00 AM EDT
Curt, how do you do that--using the marble? I wouldn't mind saving some wear and tear on my tools either. Thanks.
Link Posted: 6/22/2003 9:06:52 AM EDT
Thanks for the replies guys, I was going to try to cut it on a lathe, have any of you cut one on a lathe and if so did you use carbide cutters? Curt's booger picker method sounds interesting as well, more details please! I am not sure of the manufacturer but the barrel is 24" and marked B MP 5.56 NATO 1/9 H BAR any ideas on the origin of this barrel?
Link Posted: 6/22/2003 11:16:28 AM EDT
It's a Bushmaster barrel. BTW, guys, the most acceptable method that I've heard involved using a large slotted brass screw chucked in place of the cutter and liberally loaded with large-grit VG compound. Use that to break through the chrome and THEN switch to the 11 degree cutter. Regards, and hope this helps, FastVFR800
Link Posted: 6/23/2003 3:36:29 AM EDT
The booger picking method is easy, get a marble and slather on some valve lapping compound, sit your butt in front of the tv with a beer, and roll the marble around, pick the boo..i mean marble out now and then and refresh the compound. After an hour or so you should have a concave, very smooth crown; a matt finished marble; 1 or more empty beer cans and a few less brain cells. Thats the theory anyway i now have to get one of my kids to cough up a marble.
Link Posted: 6/23/2003 8:37:16 AM EDT
How big of a marble. Do you mean glass or like a ball bearing(steel)????
Link Posted: 6/24/2003 3:31:09 AM EDT
Typical marble size marble (it ain't rocket science its booger picking [:)]). A glass marble.
Link Posted: 6/24/2003 5:46:50 AM EDT
I ain't picking buggers. I was asking a reasonable question. Size would change the angle. I wasn't sure if a glass marble was hard enough. Had I known all of these things I wouldn't have asked in the first place. And as far as rocket science is concerned it ain't accurate all the time either(take the space shuttle for example) [b] No disrespect intended for our fallen heroes[/b]
Link Posted: 6/24/2003 6:17:41 AM EDT
ru-legal- He was just joking, not making fun of you. Calm down a little...
Link Posted: 6/24/2003 11:37:07 AM EDT
Sorry about that. I guess I read someting into it that was not meant.
Link Posted: 6/25/2003 4:42:35 AM EDT
I have used the ball and fine valve grinding compound but after I cut the new crown. I bought a Colt barrel that the original owner had cut the flash hider off of (with a hachsaw) and the muzzle looked bad. I trued up the end, cut the 11 degree crown and finished off with the ball and VG compound polishing routine. I had seen in an older gunsmith manual that this was not uncommon to do (the book showed a brass ball)and made a nice clean sharp edge on the rifling. I used the ball out of an old computer mouse -- I just took off the thin rubber skin and did just what Curt said.
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