Shortening a barrel..

[Gooddaytoya!]

Some of you may remember that I have the .6115 bore hexagonal-rifled 36-in barrel percussion rifle. My story was that the barrel wasn't fully rifled all the way to the end of the bore. So from the muzzle and back about 3 and 1/2 in it was about 58 caliber smooth round. A machinist who also does gunsmithing"fixed"this problem by reaming the end of the barrel to . 61, and somehow added some kind of rifling which he said would allow the prb to keep spinning as it flew through the defective end of the barrel. Now for my question: I want to cut the barrel down to get rid of the defective portion so that all the rifling is the original hexagonal shape. Does anyone know how many feet per second you lose per inch as you shorten the barrel? In case anyone wonders about it,, this is not a collectible rifle. It's a total oddball probably a barn find that I bought from a quote gunsmith unquote in Colorado. I couldn't make him take it back because I couldn't take legal action against him since I live in California. Thank you for any information you guys may have for me.

 

[hawkeye2]

I'm having a little trouble visualizing this so I hope you don't mind if I happen to ask a stupid question or two. The barrel was bored .6115" and rifled for about 32.5" and the remaining 3.5" at the muzzle was .58" and smoothbored. That must have made it interesting to load in its original configuration. Next a machinist/gunsmith bored it out and then rifled it, have you tried shooting it since then? If he had smoothbored the 3.5" section to a diameter equal to the bottom of the existing rifling grooves it would have been easy to load and the ball would continue to spin in the smooth section. I have seen this done in cartridge guns to repair damage when it was necessary to keep the barrel at its as manufactured length and they shoot fine. How important to you is it to keep the original rifling (in a non-collectable "barn" gun)? If it were mine I would send it to Bobby Hoyt to either bore to the next largest size or install a liner in the caliber of my choice. The last thing I would do is to shorten the barrel. I have an original underhammer with a somewhat similar situation. Someone had savaged the muzzle end bore for about 5". It had been a .36 and when I got it back from Bobby it was a .45 with round bottom rifling. An inexpensive way to save the barrel.

Some photos of the gun would be nice.

 

[Gooddaytoya!]

I'm having a little trouble visualizing this so I hope you don't mind if I happen to ask a stupid question or two. The barrel was bored .6115" and rifled for about 32.5" and the remaining 3.5" at the muzzle was .58" and smoothbored. That must have made it interesting to load in its original configuration. Next a machinist/gunsmith bored it out and then rifled it, have you tried shooting it since then? If he had smoothbored the 3.5" section to a diameter equal to the bottom of the existing rifling grooves it would have been easy to load and the ball would continue to spin in the smooth section. I have seen this done in cartridge guns to repair damage when it was necessary to keep the barrel at its as manufactured length and they shoot fine. How important to you is it to keep the original rifling (in a non-collectable "barn" gun)? If it were mine I would send it to Bobby Hoyt to either bore to the next largest size or install a liner in the caliber of my choice. The last thing I would do is to shorten the barrel. I have an original underhammer with a somewhat similar situation. Someone had savaged the muzzle end bore for about 5". It had been a .36 and when I got it back from Bobby it was a .45 with round bottom rifling. An inexpensive way to save the barrel.

Some photos of the gun would be nice.

I doubt this barrel was ever shot after it was milled. I was just wondering if there's a general rule about loss of velocity or gain of velocity per inch of barrel. I read somewhere that it's a loss of 2 ft per second per inch of shortened barrel, but I doubt that is accurate. It's hard for me to believe that a tight-fitting prb could keep spinning through 3 and 1/2 in of smooth bore. But I'll take your word for it. It's merely my assumption that this barrel can't shoot straight because of the inevitable imperfections that the gunsmith/machinist built in to the end of the barrel. I haven't range tested it yet because I've been so busy. That's obviously what I have to do. So I'll report back after the range testing

 

[Grenadier1758]

Dixie Gun Works did a test on the change of velocity with respect to barrel length. It is valid for the caliber and the unchanging powder charge. No general rule that I know about.

 

[TreeMan]

Cutting 3.5 inches off of a 36 inch barrel is gonna have so little effect on muzzle velocity that you’d never know it. 50 fps maybe? If you don’t want to pay for a rebore or a liner cutting off that amount of barrel is not going to effect anything you’ll notice. If it worries you to the point of losing sleep just add another five grains of powder to your current load. That’ll make up for any loss of velocity.

 

[martin9]

Hawkeye2 is pointing out that you have a .6115 barrel with a .580 muzzle...that doesn't work out at all for a shootable barrel. Was it perhaps the other way around? I do see where you got it reamed to .61. I'd cut it off to where it's a uniform inside diameter, nevermind fps loss...which will be small anyway.