doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com FAIR Iside response to improper regulation of brls

Chuck, old time m/l rifle barrel makers would check for straightness with a bow and a string of black cat-gut. With the breech plug out, of course, the string would be passed through the bore end to end, then attached to the bow which would stretch it tight. Then, looking through the bore towards a light source the string could be placed alongside the bore as it was rotated, revealing any lack of straightness. Barrel would be bent until the string revealed a truly straight bore.

I'm sure this method required somewhat of a learning curve, but it seems to me it could be easily employed to check for bore straightness. I've always looked at the concentric circles of reflected light, but I admit it's got to be off pretty bad for that to work, for me.

Best, SRH

Stan,
These shotguns have a lot of eyeball engineering. Nothing wrong with that if the eyeballs are good.

I bent the barrels on a pricey gun a couple months ago based on eyeball engineering, to correct a high POI. Actually, I more "straightened" them than "bent" them. They had a slight bow upward, and I took it out. It's that Italian 410 I'm refinishing. I didn't want to sink any cosmetic work into it until I got it to shoot where I pointed it. It's all better now, but I'm sure there are guys here that would have a heart attack if they saw what I did.

I was touring a heat treater for Ford and Chrysler, and I watched a couple teenager's straightening axles after induction hardening.

They just had a couple V-blocks and an arbor press. All by hand.
Locate the high spot, push it down with the press some amount to account for rebound, and move them on.

I'm confident Chuck would have had Fords axles spinning truer (sp?) than they ever had before.

Friend of mine saw an old double-gunsmith in Savannah do that, Chuck, by swinging the barrel set overhead and downward, like a sledge hammer, onto a couple bags of lead shot. He let inertia bend them until they looked like he wanted.

CZ, I straighten shafts for machinery on the farm often using my 20 ton hydraulic press. I know what you mean by "rebound" exactly. I once did a back axle for an employee's high performance four-wheeler. Got it so true by eyeballing it that he couldn't even feel it anymore at 70 mph.

SRH

A practiced eye can detect bends in a tube by looking at a straight line with a backlight, but not overly bright. Many old-time shotgun barrel men reportedly used a shop window by looking at the cross member which divided the panes.
I have not straightened a barrel by this method, but have tried it & can readily see how it works. In my machine shop days, I bent quite a few parts using the arbor press method. You always have to go a bit beyond what you want to allow for Springback.

I certainly did not mean to imply that checking for straightness was a Bad Idea, just that there are also other factors involved, so proving the barrel to be straight is not an absolute guarantee it will hit where desired.

Also over the years, I have seen quite a few doubles, particularly lighter ones, which had the barrel OD enlarged a bit at the muzzle to strengthen the choke area. This gives them a bit of a swamped effect. Looking at them with a straight edge might cause one to think they were bent, when in fact they might not be. Certainly each & every factor has to be looked at.

I should have shot a picture of the 410 Ferlib barrrels in their full over-bend, in this case on a 8 ft hydraulic Cincinnati pressbrake. But I was pretty puckered up myself. It's amazing the springback I got from these barrels. I used my friend's employee pressbrake operator and we used the machine's stop to limit the bend while the barrels were supported by wood blocks on the ends and a more pliable material in the middle where the upper ram applied force. We must have applied over-bending force at least 20 times, checking with a straight edge each time, to get the barrels straight.

Had a great uncle fall while quail hunting. Bent his A5 barrel. You could see it looking down the side or through the bore. Another old gunsmith set a couple bags of shot on the bench and he hit the barrel over them several times, checking them by sight until he was satisfied. Then had my great uncle shoot the end of a tin can at about 15 yards. Went back and whacked it again over the shot bags and told him to shoot it. Never had any problem with it again. Gunsmith said A5 barrels were easy to bend by accident and easy to straighten.

Same thing with the 20ga Rem Model 31 I started out with. Mom fell in a gully bird hunting and bent it. Country gun trader stuck it in the crotch of an Oak tree and bent it back straight...Geo

What does bending SxS barrels do to solder joints?

"John, facts are facts. Sorry if it affected you."

No affect at all


John