Barrel stress cause by contouring ?

[Pete Wass]

Pete,
My main concern is contouring done at the manufacturing, and that, because of the rate of stock removal, and possibly the geometry, and sharpness of the cutter. I would assume that if a barrel is recontoured by a smith that the rate of stock removal and possibly cutter might be different. Perhaps taking a little off with a sharp HS tool, using light cuts, fast feed, and finishing with a spinner, might actually improve the overall stress of a barrel? Yes, this is only conjecture.
Boyd

Apparently there isn't anyone who can tell you, for sure, eh? Friend Calfee says it will open the bore up - - -

 

[Boyd Allen]

According to Bill, what Buckys does to fit his tuners (threading the muzzle) is harmful to the inside of the barrel but I dont think that that has put too much of a dent in his performance, do you? It is a good thing that Bill and his worshipers have a separate board on which to exchange views. That way he won't be troubled with "funny people".

 

[crb]

According to Bill, what Buckys does to fit his tuners (threading the muzzle) is harmful to the inside of the barrel but I dont think that that has put too much of a dent in his performance, do you? It is a good thing that Bill and his worshipers have a separate board on which to exchange views. That way he won't be troubled with "funny people".

For 22 LR [ and one 22 Mag ] I have used several Anschutz "match" blanks that Numrich sells. The first one got fitted to a 40X and I left it full dia, 1.2". Later I turned it down to .825 so it would be tunable. I left the torque shoulder at full dia. When slugging the bbl with a pulled 22 LR bullet I could definitely feel increased drag at the torque shoulder. I then turned off the shoulder and used a Pac Nor nut to secure the bbl. No more drag at the shoulder location.

These old bbls have a straight bore with choke at the muzzle. Once you get the bullet past the leade it will almost fall down the bore until you reach the choke constriction. I have even felt constriction from clamping the middle of the bbl in a vise with hardwood blocks. Eye opening to say the least. Modern RF aftermarket bbls have a taper lapped bore and you would have to be sensitive indeed to feel any change in the drag on a slug due to shoulders or other exterior variations. This doesn't mean they aren't there. Does it truly affect the bullet ? Who knows.

 

[Boyd Allen]

I think that we all know that buttoned barrels' IDs can be changed by removing metal from the outside, but I also think that this may also depend on the stress relieving that was done, and how much material is removed. Also, I have not heard much about cut barrels doing this, and as we all know there are some very good cut barrels out there these days. Also I think that lead is different from jacketed in what you can get away with, and what the interior finish of the bore needs to be.

As a teaser that I cannot really discuss, a friend has been teaching himself how to relap finished barrels, in order to fix and improve their internal dimensions, and he is working with top grade barrels. The one requirement is that the muzzle be small enough in relation to bullet size so that he can end up with some choke that falls with a desirable range.

Gordy Gritters has written about, and taught this sort of thing, and probably would have completed an instructional DVD (CD?) if he had not moved away from his video resource.

 

[crb]

The current bbl I am working on came in a package with 2 or 3 bbls for an Annie 2013 which uses a clamp setup for retaining the bbl. This bbl has a .920" dia and was 21.5" long. Both dimensions are not what I consider ideal so it had a low priority. I eventually turned the breech end down to .643" and made a 1.063x16 threaded sleeve with a nice sliding fit over the .643 breech and Loctite 609'd the bbl to the sleeve and installed it in my 40X. I also recrowned and cut the rear to a cone breech.

The bbl didn't shoot worth a hoot. Borescoping looked good. Supposedly a Shilen blank. A few days ago I decided to slug the bbl and about 1/2" from the muzzle the bullet just stopped ! It was somewhat draggy all the way down the bore like a slightly tapering bore will feel. The constriction at the muzzle was so excessive that I believe the person that did the chambering didn't cut off enough of the blank and there was some of the non-lapped bore left on it.

I cut off about 1/2" and slugged it and it still was a bit much so I cut off another 1/4" and will crown it and see what happens. The bbl is now getting real short imo but the 22 sporter class rifles with short bbls shoot great so I am keeping an open mind to possibly learn something.

The other issue I has is that the .643 dimension was chosen due to an issue with the existing bbl tenon I used to make the sleeve. I believe that .643 is a bit too small to support the .920" od being hung off it plus I consider the .920" od to be too big to tune with that short of a bbl. To lighten up the bbl and create some more internal taper I plan on turning the od down in 3" segments with .050" dia difference between each segment end up with the last 3" at the muzzle being left at .920". I would have to look at my drawing but iirc the segment just in front of the .643" will be .670".