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Forums Home > Gunsmithing > barrel crowns
barrel crowns
Replies for barrel crowns
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Twinkle toes
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Joined: October 2011
Posts: 75
Location:
CRAIG, AK
Posted: February 11, 2013 4:36 PM

I have read of folks likes and disslikes, in regards to differant designs of a crown.  Why is one style of crown, any better then another, as long as it is designed to protect the rifleings? 

Twink
Zeke
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Joined: August 2011
Posts: 3911
Location:
JAMESPORT, NY
Posted: February 11, 2013 6:05 PM
Twink, I don't know all of the crowns or crowning techniques used..but some just make the end of the barrel look pretty and some actually work....back when "sporterizing" a mil-surp was the thing to do and the military barrel was near 30" long and 24" was considered to be max for a hunting rifle the kitchen table method was to wrap the barrel,once around with masking tape. take a plumber's tubing cutter and score the barrel with a nice uniform line...use this as guide to cutting it off square..then round off the utside diameter  and then dress the muzzle using a brass 5/16" machine screw and some vale lapping compound until you got a njice even recess that looked pretty.Of course you had already dressed out any tool marks and ..for the most part it worked well enough to shoot minute of whitetail...the "word' was that you didn't dress off any small burrs in the bore edge...you shot these off or made up a lead lap and lpped the bore and the muzzle edge at the same time..I even did a few dozen like this...but...now..after...putting rifles and handguns in a machine rest and shooting NM or custom loaded ammo worked up for a particular gun..I now use the tools sold by Brownells..based on an accumalation of gunsmith knowledge and narrowed down to the ........"This works best"..I'll either cut the barrel in a lathe or use the tube cutter and hacksaw(lathe if I'm using a repeatible set up tooling jig made for the barrel) or the tube cutter for the one time job  What I've added to that is the use of an aircraft counterbore of a large enough diameter to externd beyond the edge of the barrel..it is used and centered with a brass pilot of 3" in length that is a slip fit to the bore..this is used to dress the muzzle...then another C/B is used...this one of a OD that is 1/16 to 1/8" smaller in OD than the muzzle...it is ground to 11 degrees/89 degrees and is piloted with a similar brass pilot..I cut this 1/8 to 1/4' deep into the muzzle(customers preference..I like 1/4")...but the last few smidgens of material are removed being hand turned. The bore to muzzle is de-burred with a lead lap and final lap is done with a fire lapping process...I use this method on most everything that shots a bullet...the only reason I can give is that, when i handload and tune to a specific gun..the 11 degree crown seems to promote accuarcy..Why? I haven't a clue other than to say when we were building the .22 model 1911A1 conversions and using marlin micro-groove barrels(before we started pulling our own) the only tooling we had in house was the 11 degree cutters(now it is done in the machining process) When I was doing armorer's work for my Sheriffs dept and we were using S&W Model 10's and 19's and i would go over an officers gun...I would check the crown under magnification..my kit contained a piloted cutter ground to 11 degrees and I would hand spin this to dress out and dings. Every gun seemed to shoot better once this was done..Why? again I havent a clue..just that it worked in a number of different circumstances..and if you grind a couple of different OD CB and make caliber specific pilots...you can crown with out a lot of set up work......

 
Twinkle toes
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Joined: October 2011
Posts: 75
Location:
CRAIG, AK
Posted: February 11, 2013 7:19 PM
Thank ya kindly Zeke. My wife wanted me to  shorten the barrel on one of my Ruger mkIs', to make it more conveniant for when she is on here kayakin' outin's, soooo, givein' it a try! I will order the Brownell crowning tools, and thier muzzel lappin' tool.

Twink
Zeke
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Joined: August 2011
Posts: 3911
Location:
JAMESPORT, NY
Posted: February 12, 2013 9:51 AM
Twink, On a carry gun used afield, I would use a recessed crown...even as deep as a !/4" with the 11 degree cut...then treat a half dozen 22 LR cartridges with a 220 grit non embedding lapping coumpound and another 1/2 dozen with a polishing grit...400/600 and fire lap the bore and shoot the burrs off the newly cut crown..The technique for fire lapping is to limit the cutting grits,like 220, to 6 rds MAX...then clean the bore extra well, removing all trace of the prior grit. I plug the chamber and fill the bore with Kroil and let it soak for 20 minutes or so then brush and patch until no trace is left on the patch. The polishing grits can be used for many rds as they don't remove or cut metal...just shine it up.Still if you use a couple of polishing grits(I go to 900) you want to clean very well between  grits...these polishing grits will reduce leading and fouling to the point that you can go many more shots when afield without cleaning the bore. You can also treat the bore(and moving parts) with Brownell's Action Magic II...this stuff eliminates the need for  using any brush in the bore as nothing sticks to it...any fouling can be pushed out with a clean "DRY"patch.....use no solvent or oil......
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