Thread: Fast twist barrels

Originally Posted by T.FOYE

No two 'identical' barrels produce the same velocity either, further skewing any results. Or rather it could be almost impossible to make identical barrels. I reckon this question could only be answered by a manufacturer using statistics from thousands of testfires...

Something i (if i were them) would never release. The moment it became known that there was a 50ft per second advantage having 1/7 twist on any model, the 1/8 would be chopped liver and hard to sell

Yes never identical but they can get damn close. Matches guys often by multiple barrels and own there own reamer and can reuse load data from previous iterations to damn near the same results saving redoing load development. So if Bartlien does a test and limits variation even more by using a reamer sequentially limiting difference and pulling barrels from the same batch of steel and cutting them sequentially I'd say they are a pretty good authority to say that it's insignificant.
I definitely think we can conclude that the difference in the to rifles mentioned in the original post is not significantly impacted by the twist rates and is more likely a result of different batchs of powder, bore diameter, tighter chamber, faulty chromo or incorrect validation of speed.

Twist has nothing to do with velocity it is purely to stabilise the projectile, decide which projectile you want to shoot and the twist that will stabilise it
in a .223 up to 60gr 12" 69gr 9" 70-80 gr 8' 90gr 7". I had two 6mmBR's Barnard actions 30" True flite barrels chambered with the same reamer same load
one was 70fps slower than the other
It is the length of the projectile that determines the twist not the weight, The rotational speed of a fast twist can rip a light weight varmint bullet to pieces even in a .223.

Originally Posted by shooternz

Twist has nothing to do with velocity it is purely to stabilise the projectile, decide which projectile you want to shoot and the twist that will stabilise it
in a .223 up to 60gr 12" 69gr 9" 70-80 gr 8' 90gr 7". I had two 6mmBR's Barnard actions 30" True flite barrels chambered with the same reamer same load
one was 70fps slower than the other
It is the length of the projectile that determines the twist not the weight, The rotational speed of a fast twist can rip a light weight varmint bullet to pieces even in a .223.

All valid points except I wouldn't put true flite in the same repeatability league as Bartlien being buttoned vs cut and unless the barrels were made sequentially the more wear on the rifling button could partially explain any variation as could minute differences in chamber depth.

But regardless the point is moot in regards to question asked as twist rate doesn't effect velocity in any significant manner.