Twist vs velocity

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BATattack
Posts: 1275
Joined: Mon Dec 29, 2008 10:29 pm

Twist vs velocity

#1 Postby BATattack » Wed Jul 29, 2020 5:34 pm

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

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

Frank Green
Posts: 343
Joined: Wed May 28, 2014 11:48 pm

Re: Twist vs velocity

#2 Postby Frank Green » Thu Jul 30, 2020 4:01 am

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

Tim L
Posts: 876
Joined: Mon May 19, 2014 7:11 pm
Location: Townsville

Re: Twist vs velocity

#3 Postby Tim L » Thu Jul 30, 2020 11:21 am

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".
Last edited by Tim L on Thu Jul 30, 2020 8:39 pm, edited 1 time in total.

RDavies
Posts: 2318
Joined: Sun Feb 12, 2006 7:23 pm
Location: Singleton NSW

Re: Twist vs velocity

#4 Postby RDavies » Thu Jul 30, 2020 8:34 pm

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.


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