Does barrel twist influence velocity?

[TonyR]

Does anyone have a feel for how increased barrel twist changes velocity? I know that two barrels from the same same maker with the same twist might shoot different velocities with the same load, but I am trying to estimate what happens with a 6mm if I go from say an 8 twist down to a 7 or 7.5, all other things being equal.
Thanks
Tony

 

[alf]

I'm afraid you're asking a question that can't be answered definitively.

Sorry, Al

 

[rcw3]

Tony

If you are going with a 6mm, I can definitely say to stay away from a 7 twist,or be at risk of being at the position of not getting a lot of velocity out of the barrel without a lot of pressure). I have had personal experience with two 7 twist barrels and know of others who tried them and had the same problem I had,i.e. a lot of pressure for the powder charge and velocity). I never saw this condition in the 7.5" twist barrels I have, but a 7" is just that much more tight enough that is can be "over the line". If you are running 115's, go with a 7.5" twist and no tighter. If you are going to run the 105-108's, an 8" twist is ideal.

Robert Whitley

 

[TonyR]

The 115 VLD is the issue. I have been shooting round holes out to 1000 yards with them out of an 8 twist Kreiger but so far only on 80+ degree days. So far, with the same powder charge, the velocity loss seems to offset the gain in BC versus the 105 VLD. Some very preliminary testing suggests that "the sweet spot" with the 115 is at a heavier charge than with the 105 VLD,all Bergers) which implies that I might have the opportunity for a net gain. I just don't want to give it all back by going to a faster twist. I would not go below a 7.5 in any event because the 105s shoot great verticle. I was just hoping the reduce the wind drift a bit with the 115s. I guess I'll just keep testing into the cold weather and see if the holes stay round in the 8 twist.
Thanks
Tony