May be that is what I was hearing, and yes I let mine air cool to. Also I agree I love the Maxi-ball. I'm not sure that barrel twist has as much to do with the bullet being accurate has we think. The thing I found funny is, I'm biulding a 10/22 for my son, to improve accuracy with sub sonic bullet I'm going to use a 1:6 instead of a 1:16 twist which is the standard twist for most 22 cal. These barrels are made for the bigger slower bullet. However in a muzzle loader they say I need a 1:38 or slower to shoot a bigger slower bullet. Go figure!