Originally Posted by CCMachinist
I don't know how they rifle the barrels. If I could get a raw tube rifled I could make some.
Other than that I'll have to give it some thought.
I have a T9.1 rifled barrel from LAPCO specifically made for first strikes (though I am not sure the twist matches the pitch of the fins on the FS). The grooves do not, but then the body of the FS has a slightly larger OD than the fins and is what engages the grooves.
The grooves are shallow and squared off. It does give the FS a little start on rotation to avoid the wobble that they get from a smooth bore barrel while they start their rotation.