I just recently upgraded the power of my .25 cal. Airforce airgun to where the 51 grain BBT will work. It has a 1-16" twist LW bbl. with .254" groove dia. Both bullet's driving band sizes fall outside of my needs of .253". If I can help it I do not want the additional step of resizing the .255's. Ideally the bullets would drop out at .2535", according to what I've read. Would it even be possible for me to resize the driving band of the .252" mould? And even if I could, would that work well, or not, in a .254" bbl.?
MatchBased on my testing so far with hundreds of designs of bullets I start to get a feel of what works and what does not. Of course, mainly influenced by the guns I own or have access to. I believe these boattail designs only work when the bullet is long and heavy. The bullet you want me to try is even shorter than the one I already tried.It is not just the BBT. Same thing when I swage a full length boattail - they are not stable. Bob could be right and you need a very fast twist rate to stabilize it. Problem with that is most guns do not have that and I make ammo for "most" guns not for a few custom guns. So if you need a 14 twist or faster to do so, I do not know of any barrels on production guns for .250-.252 with 10-14 twist rates so only a few guys who rebarrel or have customs guns could potentially buy it from me. I hope I am wrong because no one wants this to work more than me, except maybe Bob .