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Edgsmth
June 21, 2007, 20:45
What is the most popular/best crown for an FAL barrel? 11 degree?

Survey Punk
June 21, 2007, 21:45
As long as it's clean and free from dings, burrs, etc. don't worry.
I don't think any sort of fancy crown is going to make that much diffference.

JB

Radio
June 22, 2007, 01:05
11 degree is what I see the most around the 'net.

Of course, Imperial Margarine will put a crown on anything, I done seed it on TV.

--Radio

jay.sharkbait
June 22, 2007, 02:42
just something clean.

Any super duper target crown is like putting a gold tooth in a dead dog


bait

mountainman
June 22, 2007, 09:28
Oh that crown has plenty to contribute. As the bullet exist teh barrell, a good face and good crown see to it that the gasses blow by the bullet in a perfectly concentric manner and doesn't bias it to any other direction except for perfectly straight forward. Got any knicks and bumps in that crown face and the bullet will have bias. But whatever you do, don't do it by freehand, it will only get worse. Then you end up putting a dead dog on a gold tooth.

ratas calientes
June 22, 2007, 18:15
Make it 13 degrees to match the locking shoulder angle . . . . or was that 12 degrees? My memory is fading with time . . . . :tongue:

http://chilirat.com/emoticons/chilirat.gif

Radio
June 22, 2007, 18:30
You, sir, are a turd.

Dang funny turd, though. :tongue:

ratas calientes
June 22, 2007, 22:24
Originally posted by Radio
You, sir, are a turd.

Dang funny turd, though. :tongue: Luv ya, man. http://chilirat.com/emoticons/chilirat.gif

Deltaten
June 23, 2007, 14:55
mountainman sez: "don't do it by freehand...."
LOtsa "booger pickers" here will differ there MM :) I have improved accuracy on a couple bbls by using one of several methods of "freehand" crowning; and find no diff in the result.
Not saying a machine cut and finished crown is no good or not better; just that such a broad statement is a bit ..well...uh.. broad! ;)

Wonder if such a result could be done a'purpose...
take a bbl that shoots irregularly high or low..whatever..
crown it "off', so that the odd angle crown WILL allow all that gas to pass and the bullet base to grip one side longer than the other. See if it really does change POA/POI .
use this new method to sigh a poorly done bbl wrenching..I mean... if it changes POI soooo much; why not use that to advantage and correct sight/bbl probs w/it ??? ;)

Best
Paul

mountainman
June 24, 2007, 06:40
If that crowning is not perfectly centered and skewed, so will the bullets flight be affected. You stand to mess things up by doing it by hand with a cutter that isn't piloted to the bore. I'm not saying things must be done on a lathe ( you could also mess things up there too) I am rather partial to the piloted handcutter method. But taking a angle chamfer tool and doing it with a handrill will cause some problems.

brownknees
June 24, 2007, 08:34
I don't think thik this will work on a match type crown, but it has helped on a couple of battle rifles where the crown was nicked. I also wouldn't try to make a crown from scratch this way.

I've used a round headed brass bolt, chucked in a power drill to rescue a couple of these using valve grinding compound as an abrasive polish.
If you get a bolt where the head sizes is such that the approx 30 degree part of the curved surface contacts the bore & SLOWLY rotate a LITTLE & polish lightly, then it will remove dings, but not make a big change to the undamaged part of the crown. Both times I had to do this it did improve accuracy back to normal. It didn't improve accuracy, just restored it.

Use a magnifying glass to check regularly & stop when there are no more marks visible.

Don't forget to remove all of the compound by pushing out & away from the bore, while cleaning a lot.

olsarg
June 24, 2007, 10:54
Try using search on the gunsmithing forum. Believe lots of falers use the glass marble method.

mountainman
June 25, 2007, 07:26
Ahh, the Midway way. How can you rest assured teh crown you acchieve is perfectly concentric to the bore? No Pilot.