Barrel twist effect pressure?

[Rhovee]

So the question that I have is if a barrel twist has a slight taper towards the end would that make it have more pressure than one of less twist? Say a 1:8 twist compared to a 1:8.5. It makes sense thinking about it. That if the bullet has to be pushed and twist more the barrel would have more pressure? Say all things being equal, you had two barrels shooting side by side, would you get less pressure out of the less twist.

 

[elkaholic]

Short answer is yes, but the main concern is accuracy/stability and the difference in pressure/velocity between 8 and 8.5 is marginal.....Rich

 

[tim_w]

It's effect can also vary based on caliber, bullet bearing surface, etc. Rifling llands size (ratio to groove area) and then type and configure has more of an effect. Used in combo along with bore surface treatment it can increase vel and lower pressure but for most the extra my not be worth the extra time cost and headache.

We did a fairly good amount of testing with many different rifling and twist configure using barrel pressure testing and chronograph equipment.