Rifling Twist Rate and Barrel Length

[chicharrones]

Regarding twist rate and barrel length, does a more completed rifling twist make much difference?

Meaning, if a 16" barrel has 1 complete turn of rifling and a 24" barrel has 1.5 complete turns, does this affect accuracy at all?

I am contemplating shortening the barrel of a .22WMR rifle I have to make it more compact. In this case, shortening a sporter profile barrel in a bolt gun from 22" to 16.5".

 

[rcmodel]

No.

The bullet is engraved by the rifling as soon as it leaves the case.

It is up to full rotational speed as soon as it is engraved over the full length of the bullets bearing surface.

If was slipping all the way down the barrel trying to get up to full rotation?

The barrel would be completely packed full of leading or jacket fouling after the first shot or two.

And handguns wouldn't work at all.

rc

 

[CraigC]

No but be advised, you're going to gain a lot more noise cutting the .22Mag back to 16" and probably lose a little velocity.

 

[chicharrones]

Thanks for the feedback, y'all. I definitely would expect a louder gun and some velocity loss.

 

[4thPointOfContact]

"Completeness", no but barrel length can.
A longer barrel that produces higher feet/sec will stabilize a bullet better than a short barrel A spinning top spinning at 300rpm is more stable than one spinning at 60rpm even if both spinning tops weigh the same.

Bullet stability is an interplay between twist rate, projectile lenght/weight, velocity, and rotational speed. The reason the Army went with the 1:7 rate is because the 1:9 originally tested would not stabilize the M856 tracer during Arctic testing. The M856 is longer than the same weight M855 and cold air is denser.

If it were not for that, the Army would more than likely have gone with a 1:8 twist.

 

[chicharrones]

Thanks for the reply, 4POC.

RPMs, indeed.