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View Full Version : General smithing question.


Irving
11-29-2009, 15:02
I'm going to SBS my 870 one day. When that day comes, can it get it cut and threaded again so I can still use chokes?

Thanks.
kwando
11-29-2009, 17:37
Stu you are probably better off just getting another barrel
Irving
11-29-2009, 19:19
I don't know where to pick up a choked 12" barrel.
BPTactical
12-09-2009, 18:36
With a 12 inch barrel the choke is pointless.
Irving
12-09-2009, 18:40
Why? I've always been curious if a 12" barrel with no choke will yield the same spread as a 26" barrel with no choke; if you move forward 14" when shooting the 12" gun.

Can you go elaborate a little?
BPTactical
12-09-2009, 21:46
Why? I've always been curious if a 12" barrel with no choke will yield the same spread as a 26" barrel with no choke; if you move forward 14" when shooting the 12" gun.

Can you go elaborate a little?


Here is how it was explained to me:
The powder charge has enough dwell time to burn fairly completely in a long barrel.
When the wad/shot is in a longer barrel say 24 inches the gases from the powder charge have a controlled rate of expansion resulting in an even "Shove" to the wad and shot combo. A smooth "shove" will stabilize the wad/shot as it is traveling down the bore and let the choke do its job the way it is intended. The expanding gases have slowed slighly and pressures have dropped and will follow the wad/shot out of the muzzle and wont try to overtake it.
Now consider that in a short barrel the charge does not combust completley before the wad/shot reaches the muzzle. Instead of the smooth shove the wad/shot has now gotten a violent "kick" of propulsion with expanding/combusting gases basically exploding the instant they reach the muzzle and "kicking" the wad/shot in the ass and trying to overtake it. This results in enough instability to render a choke virtually useless. Plus the wad/shot is not in the bore long enough to stabilize it very well.
Now also consider the fact that you could blow the choke right out of the end of the barrel due to the pressure being very high at 8 inches away from the chamber.
Typically you will find most all barrels shorter than 20" are only cylinder bore, which means no restriction to the bore.
Irving
12-09-2009, 22:15
I had a feeling that it had to do with the burn rate of the powder, but I don't know anything about shotgun barrel lengths and stabilizing the projectiles. However, I can't imagine that anything is going to be more violent than the initial explosion in the chamber. I'm pretty skeptical of the concept of a choke acting like a severe enough bottle neck that it'd blow the choke right out the end of the gun; however, like I said, I really just don't know.

I wish I had enough funds to do both and do a little experimenting.
Irving
12-10-2009, 18:21
BPTactical, is rechoking a barrel something that is possible though? Would you do it for me if I signed a release waiver or something?
BPTactical
12-11-2009, 18:05
BPTactical, is rechoking a barrel something that is possible though? Would you do it for me if I signed a release waiver or something?

I will do a little research and touch base with you.