OzFclass

Hear a lot of debate on this so might be useful info

http://bulletin.accurateshooter.com/202 ... ist-rates/

Not only did we make all those barrels in the test but we chambered them as well. So same chamber reamer was used in all of them and the barrels where all made at the same time. If I recall correctly all of the barrels where made out of the same lot of material except for the left hand twist was out of a new lot. So about as identical as you can make them.

It's always been my understanding that twist might have a small impact on velocity but for the most part it really doesn't in the grand scheme of things.

Later, Frank
Bartlein Barrels

What a great test.
IMHO that test confirms the difference is insignificant. 8fps (0.3%) is within what most achieve in velocity variation of a tuned load in a competition barrel.
The full spread from slowest to fastest projectile is only 22fps. From my experience that's maybe a 0.1-0.2gn powder adjustment or a jump adjustment. Seeing those sorts of figures over 6 different barrels tends to suggest "nothing to see here".

I think it was Harold Vaughn who did these similar tests a while back and found a similar thing, negligible difference in velocity from twist rates.