B22 barrel chop question

B22 barrel chop question

Joined: April 19th, 2001, 6:33 pm

April 1st, 2002, 6:59 pm #1

Well i am thinking I would like to cut the barrel length of my B22 to the optimum lenght needed. I am wondering who out there has cut the barrel on the B21/B22 and what length worked out best. I assume if a gun like a TX200 can get away with an 8" barrel the B22 can go substantially shorter than the stock lenght, I am thinking of cutting it to 15" from the stock 20". Any tips or experience appreciated!
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Joined: May 1st, 2005, 9:00 pm

April 1st, 2002, 8:27 pm #2

but gained a little accuracy.
The TX was designed from the ground up for a short barrel.
Last edited by doratis on April 1st, 2002, 11:07 pm, edited 1 time in total.
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Joined: April 19th, 2001, 6:33 pm

April 2nd, 2002, 1:24 am #3

James, so in your exerience shortening barrels on these was there any advantage at any length? Was this a B21 or B22 you shortened? I would imagine due to the volume of air and the bore size you could cut the .22 verson a little shorter than the .177 before effecting velocity. There must be some formula for stroke length of the compression tube, diameter of the tube and the bore/barrel to figure out at what point downt the barrel the pellet is no longer under infulential pressure. I suppose I could try to calculate it, anyone know what the bore specifics for a b22 are, or this formula?
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Joined: May 12th, 2001, 1:29 pm

April 2nd, 2002, 2:32 am #4

...better luck than I did.

I worked up a numerical simulation of springer internal ballistics that seemed to look pretty realistic. It predicted that the optimum barrel length for max MV with a 7.9gr pellet (primarily determined by the duration of the piston pressure pulse) for a .177 B18 is 10".

So you can imagine my chagrin when I chopped a B18 to 10" and LOST 40 or 50fps with CPLs over the stock 18" barrel length!

Now the best I can get from my B18 carbine shooting CPLs is 812fps -- 11.6fpe. I, like James with his B22, think I see improved accuracy (maybe due to the shorter lock time), but it did cost about 10% in ME.

Let us know how you get on.

Cheers,
Steve
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Joined: April 19th, 2001, 6:33 pm

April 2nd, 2002, 2:43 am #5

Steve, well it looks like you already tried my thoughts out. there must be some portion of the equation that takes into effect the compression of the air and what that does to the volume of the chamber. But who knows, it probably doesnt take much to be off alot, like if you are off on the stroke volume just a bit that would really screw up figuring out barrel length as a little air in the chamber is alot more in barrel length. if this was a .177 gun (B21) i would not worry about 40-60fps, but thats alot out of a B22 velocity. Maybe I oughjt to get used to the length!
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Joined: January 25th, 2002, 3:42 pm

April 2nd, 2002, 3:07 am #6

It sounds interesting to me cause I have a B22 too. I think there is more to figure in than bore and stroke and how much that displacement will fill the barrel. A big thing would be the microseconds of extreme heat from the air being compressed so high. In another instant the air is cooled back down by the ambiant temperature of steel around it. Any ways air expands when it is heated and that is part of the equation for optimum barrel length. Also I talked to James about his barrel shortening experiments. I may be wrong but I think he was only doing it on .177 B21 rifles, not the B22, I apologise in advance if I am wrong on that. Bottom line is, I want to encourage you to try a barrel chop on a B22. I'd like to know your results. I already put a muzzle brake on my stock barrel so I'm not in a hurry to cut it off...yet.
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Joined: January 27th, 2002, 6:17 am

April 2nd, 2002, 4:25 am #7

but gained a little accuracy.
The TX was designed from the ground up for a short barrel.
of my B21, it shows the piece of barrel I removed along with the other "Extensive" work I did to "Sporterize" my B21. BOTTOM LINE: Shoots better than before for accuracy, I haven't chrono'd it so can't say if lost speed but it sure doesn't seem like it. Overal length is now 37 1/2" and it weighs in at about 7 1/2 #'s.
see sight below for pics posted back in January:

Modified B-21, by Airheaded.
January 8 2002 at 8:53 AM Eddie (Login Adiberts)
from IP address 66.50.82.179

--------------------------------------------------------------------------------

Go and see the great job Airheaded did on a B-21 modifying it.
http://home.talkcity.com/PhatAirRd/mast ... dified.htm


Regards,
TF79shooter aka airheaded

TF79shooter

Keep em in the black!
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Joined: October 21st, 2000, 9:30 pm

April 2nd, 2002, 5:47 am #8

Steve, well it looks like you already tried my thoughts out. there must be some portion of the equation that takes into effect the compression of the air and what that does to the volume of the chamber. But who knows, it probably doesnt take much to be off alot, like if you are off on the stroke volume just a bit that would really screw up figuring out barrel length as a little air in the chamber is alot more in barrel length. if this was a .177 gun (B21) i would not worry about 40-60fps, but thats alot out of a B22 velocity. Maybe I oughjt to get used to the length!
even though a choke is a restriction in the barrel, it also helps short barelled guns achieve higher velocities. When you cut the choke off a choked barrel, things are bound to happen. RB

Russell Best
BesTunes
BSA Owners Club
C.O.P.S.
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Joined: August 22nd, 2001, 3:27 pm

April 2nd, 2002, 12:35 pm #9

Well i am thinking I would like to cut the barrel length of my B22 to the optimum lenght needed. I am wondering who out there has cut the barrel on the B21/B22 and what length worked out best. I assume if a gun like a TX200 can get away with an 8" barrel the B22 can go substantially shorter than the stock lenght, I am thinking of cutting it to 15" from the stock 20". Any tips or experience appreciated!
reduce the transfer port diameter a little, I would try about .003 smaller. This will boost the velocity of the air passing through the port, The volume of air reaching the pellet will be reduced, but then the barrel is now shorter, and should not requier as much air volume. Good Luck James P.
Last edited by jpsaxnc on April 2nd, 2002, 12:52 pm, edited 1 time in total.
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Joined: April 19th, 2001, 6:33 pm

April 2nd, 2002, 2:59 pm #10

even though a choke is a restriction in the barrel, it also helps short barelled guns achieve higher velocities. When you cut the choke off a choked barrel, things are bound to happen. RB

Russell Best
BesTunes
BSA Owners Club
C.O.P.S.
Do you know whether the B21/22 come with choked barrels? That makes sense what you say, good point.
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