Jefferson
I have done quite a bit of velocity testing with my 6PPC over my 35p Chronograph. Anything above 22 1/2 inches produces such a small gain that I decided to keep the barrel as short and stiff as possible. Just my way of thinking. In fact, I still get over 3400 with a sub 20 incher.
Sometimes, though, I wish I would have left a barrel longer. For instance, that really great barrel that is on it's fourth setback, and still shoots quite well. If I would have started at 24, I might have got even more out of it.
It is amazing how some barrels just keep shooting as long as yopu keep a decent throat in it.........jackie