I shoot air rifles and am looking for a .22 barrel that will stabilize a 44 gr .22 soft lead boolit at 1000 fps or a bit less. The online twist calculators that let you input a speed variable either tell me I'm shooting too slow, or recommend a 1 in 10" twist. My present barrel is a 1 in 17 1/2" twist and will group boolits in an inch at a bit beyond 40 yards. The targets show some yaw at 40 yards, and at 60 yards the boolits still don't keyhole but groups open to two inches.
I am thinking of getting a Green Mountain barrel for a .22 mag with a 1 in 14" twist. I don't want to lose the ability to shoot regular waisted pellets if I can help it, so I'd like to stay away from a larger bore center fire barrel. The basic Greenhill formula makes it look like a 14" twist should work for me, but before I spring for a barrel, I want to dip into the knowledge base here.... experience trumps theory in my book.
If I need a dedicated "boolit barrel" in a 10" or 12" twist, so be it, but I'm hoping the .22 mag barrel will work in both worlds... pellets & boolits. Any advice ya'll can offer is welcome. Thanks... Mike