ask about big bore airgun barrel, twist and rifling
dear, friend
I’m new at this forum but I’m interesting to join.
I have a few airgun like condor(I regret have sold it), hw-97k, hw-80.
and recently have hunting safari at sumatera island, found hundred wild hogs, etc.
I’m interesting to built powerful bigbore airgun like quackenbush built, but I had question at the barrel twist and rifling number, my friend use standart or sometimes firearm barrel but fail to get high velocity and accuracy.
does big bore airgun that use heavy grain bullet use different twist and rifling? compare to standart airgun? or I can use firearm barrel?
what is the specification for this purpose and who can supply me the barrel?
may be 7mm, 0.44 or 0.45 cal
thanks
markus
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The Koreans seem to do well with their airgun barrels, so I suggest emulating their barrel specs.
In .45 caliber, that’s 1-20 twist (I hear 1-18 works good, too). I’m guessing that the bore is probably .450, with the rifling being about .456 choking down to about .454 at the muzzle, so the rifling is very shallow at about 3/1000’s.
As for rifling, in a firearm, pressures can reach 50,000+ psi and will “smash” the bullets to fit the bore. In an airgun, thin lead skirts are used for the same purpose. Bigbore airguns that shoot cast bullets need a way to seal the bullet to the bore, and this is achieved through the use of soft bullets, sabots or shallow rifling. But it is not an exact science yet and some have achieved excellent results 45-70 and 32-40 barrel liners.
thanks for the info but still need more specific what twist and rifling for cast bullet airgun barrel.
For the twist it would probably be best if you contacted Chubby Checker as he invented the ‘twist’. 😆
As for rifling, in a firearm, pressures can reach 50,000+ psi and will “smash” the bullets to fit the bore. In an airgun, thin lead skirts are used for the same purpose. Bigbore airguns that shoot cast bullets need a way to seal the bullet to the bore, and this is achieved through the use of soft bullets, sabots or shallow rifling. But it is not an exact science yet and some have achieved excellent results 45-70 and 32-40 barrel liners.
thanks for the info but still need more specific what twist and rifling for cast bullet airgun barrel.
To put it simply, different power sources require different twist rates and barrels. Most powder-burners fire projectiles at much higher velocities than an airgun of a similar bore diameter. This difference in speed means that the barrel will have to have a different twist rate. Projectile lengths also come into play and I am not knowledgeable enough to explain the forces at work.
As for rifling, in a firearm, pressures can reach 50,000+ psi and will “smash” the bullets to fit the bore. In an airgun, thin lead skirts are used for the same purpose. Bigbore airguns that shoot cast bullets need a way to seal the bullet to the bore, and this is achieved through the use of soft bullets, sabots or shallow rifling. But it is not an exact science yet and some have achieved excellent results 45-70 and 32-40 barrel liners.
Viewing 5 replies - 1 through 5 (of 5 total)
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Here ya go…you’ll need to supply the details.
http://kwk.us/twist.html