Powerloss by shortening a barrel. Question?
Powerloss by shortening a barrel. Question?
Hi I just want an estimate of how much power I would loose if a barrel of approximately 21.5 inches was shortened to 10 inches. With the 21.5 inch barrel the rifle shoots 470 fps. Alternatively what if it was shortened to 6 inches?
I guess I could have put this in the Mods and repairs forum.
I guess I could have put this in the Mods and repairs forum.

yeh, realy depends on the gun and the power plant.
Magnum springers with long barrels have been known to GAIN a couple fps when choped down to around 15", and to loose only a bit with each inch shorter. In contrast, with co2 and the longer the better.
thats a realy long barrel...what is is a Slavina 630?
Magnum springers with long barrels have been known to GAIN a couple fps when choped down to around 15", and to loose only a bit with each inch shorter. In contrast, with co2 and the longer the better.
thats a realy long barrel...what is is a Slavina 630?
Well I did figure that quite a bit a bit of power would be lost. :9 But I'd like to bring the barrel length down to atleast 13 inches. Anyone know if even that might be possible without loosing a ton of power??
Joben - yes it is a Slavia 630. I am modding it for a project I am working on, and shortening the barrel is pretty must completely nessecary. I wonder if a can get a stronger spring for it or something.
Joben - yes it is a Slavia 630. I am modding it for a project I am working on, and shortening the barrel is pretty must completely nessecary. I wonder if a can get a stronger spring for it or something.

Cardew's Experiments
Cardew, Cardew, & Elsom did extensive research on barrel length and other aspects (piston, mainspring, transfer port, lubrication etc.) of spring airguns.
They published their results in "The Airgun from Trigger to Muzzle" in 1976 and in the subsequent "Trigger to Target" updates.
I consider the books a "must read" for spring gun tinkerers.
They found barrel length to be an insignificant factor.
Transfer port size, barrel chamfer, fuel combustion etc. were far more critical to velocity.
On a Weihrauch HW35 in .22 they discovered that velocity peaked in 6" of barrel and remained constant until 25".
Velocity then decreased due to friction.
The Slavia 630 in .177 would probably yield slightly different numbers but I would bet that the 10" barrel chop will not affect velocity.
I've made a couple of 8" barrelled buccaneer pistols out of $25 Chinese POJ .177 air rifles and noted no power drops.
They published their results in "The Airgun from Trigger to Muzzle" in 1976 and in the subsequent "Trigger to Target" updates.
I consider the books a "must read" for spring gun tinkerers.
They found barrel length to be an insignificant factor.
Transfer port size, barrel chamfer, fuel combustion etc. were far more critical to velocity.
On a Weihrauch HW35 in .22 they discovered that velocity peaked in 6" of barrel and remained constant until 25".
Velocity then decreased due to friction.
The Slavia 630 in .177 would probably yield slightly different numbers but I would bet that the 10" barrel chop will not affect velocity.
I've made a couple of 8" barrelled buccaneer pistols out of $25 Chinese POJ .177 air rifles and noted no power drops.
- DoctorFrankengun
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Re: Cardew's Experiments
Photos, we want photos [-o< [-o< [-o<RossB wrote: I've made a couple of 8" barrelled buccaneer pistols out of $25 Chinese POJ .177 air rifles and noted no power drops.
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- DoctorFrankengun
- Posts: 1657
- Joined: Thu Sep 08, 2005 1:58 pm
- Location: Cochrane, Ontario Canada
Jan,
It seems a shame to chop a fine gun like the 630. Can't you find a cheap POS or a used gun?
It seems a shame to chop a fine gun like the 630. Can't you find a cheap POS or a used gun?
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