doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Gun reboring and regulating.

Glad you found it interesting, Mike. Last year about this time I posted on here about my previous attempt at making a sxs turkey gun. I bought a cheap Yildiz and had the barrels cut to 24", shortened the stock and added a thick recoil pad, and got the weight down to 5 lbs 2 oz. It shot field loads fine, but shot wall-eyed with the turkey loads - right barrel shot right and left barrel shot left. It was a problem I couldn't solve, so I had Brileys make eccentric chokes and made the gun usable, but it didn't throw very good patterns. Since I know how to file a choke now, I'm gonna try filing one of the cheap chokes I have for it and see if it will be an improvement over the eccentric chokes. Only problem with the Yildiz is that it doesn't have enough triggers.

I'm not sure I understand some of the discussion in this thread, but I thought that all sxs guns had barrel convergence to account for the recoil. If they were perfectly parallel, I'd think they would shoot wall-eyed unless you were using extremely light loads. My thinking is that my Spanish gun was set up with too much convergence, while the Yildiz had the correct amount but it was meant to shoot light field loads. Both barrels of it shot to poa with 1 oz loads; the gun does what it was meant to do and I'm trying to do something with it that the makers never intended. The Spanish gun originally wouldn't shoot anything to poa; I think this was just a flaw in the way its put together.

Its really easy to see the progression in the Yildiz, especially in the right barrel. The heavier the load, the more it shoots to the right. I think to get a light weight sxs that will shoot heavy loads to poa, I'd have to get someone to make me a gun with more convergence than normal. That, or take a file to it, and I gotta believe that is a detriment to the patterns. The Yildiz threw excellent patterns with straight chokes; it just wouldn't center them. The Spanish gun shoots better patterns than the Yildiz does with its eccentric chokes, but they still aren't as good as what its possible to get with a special turkey choke.

The combination I'm using of lightweight guns and heavy loads no doubt exaggerates barrel regulation problems. For most of the readers here, it might never be much of an issue.

Thanks to all for the great info posted here. I don't post often because I don't have the level of knowledge of the regular posters here, but maybe some of my trials with my turkey guns will help someone with a barrel regulation problem.

I know many will cringe at the idea of taking a file to a nice sxs, but remember that these are cheap guns that I am experimenting with for the fun of it more than anything else. I don't plan on chopping up a nice sxs.

Mike,

S x S barrels are not curved the way you say. this is an optical illusion that is created by the way the barrels are turned, then struck. Plus, it is exacerbated by the fact that you cannot see the same curves on the inside, between the ribs. I have removed the ribs from S x S guns and that illusion goes away. They then look perfectly straight, as they are.

The easiest way to tell if any barrel is not straight is by looking down the bores at the concentric rings made by the light reflecting at different distances from the eye. If the barrel is straight the rings will be evenly spaced all the way around. If not, they will be closer together on the side with the "inside of the curve". This can be done with smoothbores and rifled barrels as well, though it is a bit easier with a shotgun for me.

SRH

Stan if they are perfectly straight then there are a lot of barrels shooting cross-eyed.

The angle between the two barrels is different for different guns. A Parker 2 frame 12 gauge with factory 26" barrels has a different angle between its barrels than a Parker 2 frame 12 gauge with 34" barrels.

The Skeets gunsmith agrees with me.

Mike, are you folks thinking both barrels curve enough that the muzzles have some parallel segment. At the muzzle end, are both barrels looking parallel, not cross-eyed. And, they're shooting parallel to each other.

There ARE a lot of them shooting crossed. I have run into many that were not regulated. IME, when a S x S is not regulated it is usually shooting across, i.e. the left bbl will print too far right, or the right barrel will print to far left. The bore rings don't lie, Mike. They cannot be perfectly round and concentric if the barrels are not straight. Look down the bores of a really clean barrel at them.

I watched a Beretta video awhile back, made at the factory. One of the segments was about a craftsman there who was a barrel straightener. That's all he did, straighten tubes to perfection with a press. Not a barrel curver, but a barrel straightener.

SRH

P.S. I agree the barrels are angled, in relation to each other, and the angles are different on different guns. But, they are angled without being curved individually.

SRH

Mike and anyone else. Joe Wood sent me the Nov. 1937 American Rifleman article "Making Double Shotgun Barrels" by A.P. Curtis some time ago. He discusses barrel straightening and joining. "Great care here is necessary to see that the tubes lie in the same plane, and are properly adjusted to prevent cross-firing."
I'd be happy to forward the article to anyone if you'll e-mail me at revdoc2@cox.net

No. When the right barrel is fired I think the barrels rotate to the right as the shot goes down the barrel and that the muzzle is both displaced and moving to the right as the shot comes out of the muzzle. Of course mirror image when the left barrel is fired.

The O/U hangar Kreighoffs have hangars that adjust the vertical point of impact from one barrel to the other. If you want the POI the bottom barrel to move up you put in a shorter hanger. If you want the POI to move down you put in a longer hangar. Adjusting POI by curving the barrels does not require a press.

Fact #1;
Drawing for L C Smith 30 12ga FW barrel. C/l's at breech separated by 1.156", at muzzle by .8175" for a taper in 30" of .3385" or .0113" per inch. Continuation of bore Axis cross at 72.452" from muzzle or about 6 feet & a half inch. A continuation of bore axis to 40 yards shows a cross point of 15.43"
Fact #2;
The impact of the center of the pattern is Not exactly to the same place the bore points in a static position, if it were ALL doubles as built would cross fire.

Hear-Say;
Rule of Three:
My Third Wifes Third sister's Third Father-in Law worked for a gunmaker in '33. He was employed there for Three months, but they fired him. Reason, he insisted on bending the last Three inches of the barrels so they would lay parallel to Shoot to point of Aim. The company didn't want that bu he insisted it had to be done that way so the barrels would shoot together. They told him they didn't want them to shoot that good, if people missed a lot more they could sell Three times as much Ammo.
Ain't it kinda funny how many people would buy that, that won't buy established FACT.

Miller Joe Wood talked to the Skeets gunsmith a couple of weeks ago. Joe Wood relayed that part of the conversation to me. Joe Wood acknowledged in a previous post on this thread that that is what the smith said. No third wives, third sisters, third father-in-laws involved.