re: How I Barrel A Precision Custom Rifle - Long Rifles, LLC
I don't. Seriously. What good does it do? Think about it. I do support it with a 5C collet in a little doo dad I made, but that's it. I don't indicate the opposite side of the barrel. I'd be bending the barrel if I did.
I'm more interested in keeping the bore tangent to the bearing surface of the bullet. You can't do that if you "muscle" the crown side to spindle center.
Sounds crazy I know. It was an experiment I did some time ago and after discussing it at length with a very bright/experienced mechanical engineer I (we) concluded its not hurting anything and may actually be HELPING.
Lets put it into perspective. lets say the OD of the barrel is out of concentricity with the bore by .005". A typical barrel blank is 28" long when it shows up in the mail. The angle of deflection (if my math is correct) is .0102 degrees (double that for the included angle over 360* of rotation). Given a choice I'll gladly give up that value over 28 inches if it means better surface finishes, thread fits, and chambers that come out with less than two tenths of runout.
Proof is in the pudding so high minded discussions don't mean much till lead starts hitting backstops. The most recent build I've completed is the little 22BR gun that I've splattered all over internet land. At 100 yards I was recording 5 shot groups at a half inch with relabled Eley Black box (Match EPS) Remington ammunition. The owner has a tunnel and he's getting .266" for an average at 50 yards. That's with one box of ammo randomly picked from his stash. He hasn't even begun lot testing yet. Take that along with the historical track record my rifles have and I feel pretty good about the direction I'm heading.
The famous Mr. Gordy Gritters uses a procedure that is not all that dissimilar from the one I have chosen. (set up wise) I didn't know this till just last week. I find it fascinating that two guys completely independent from one another come to what is basically the same process. Kinda cool.
There are a great many "10 commandments" in gunmaking/accurizing that exist today. They are regurgitated over and over because "that's just the way its been done". Many are valid but there are some that I really don't agree with.
Sometimes the box just needs to have it's walls kicked out.
You ask a great question. Hope I answered it to your satisfaction.
All the best,
Last edited by NesikaChad; 06-02-2010 at 01:17 PM.