Velocity v. Barrel Length

[Ganderite]

Shooters are always wondering about how much velocity they gain or lose by changing barrel length.

My range has a Chrony, so today I logged the velocity of some revolver loads I was testing, and made a point of shooting them through a 2”, 3” and 4” barrel (all S&W 38Spl. revolvers).

Winchester factory 148 WC
2” 674fps
3” 684
4” 715

Handload 3.2gr TiteGroup 148 WC
2” 774fps
3” 810
4” 861

In round numbers, there is not much difference between a 2” and 3” barrel. A 4” barrel boosts velocity only 6% to 11% over a 2" snubby. Not as big a boost as I would have guessed. This is why it is good to have a Chrony.

 

[saskgunowner101]

I wonder how different burn rates of powders might affect the velocity as well. Be interesting to see with a slower powder (Unique, BlueDot etc) if there would be more velocity gained.

 

[Juster]

What chambering were you using?

 

[Ganderite]

All were chambered in 38 Spl.

 

[misanthropist]

http://www.ballisticsbytheinch.com/

 

[RememberTheSomme]

Thanks for posting results Gander. It's always nice to see real world reports for comparison.


Heavy bullet weight's with slower burning max charge weights even in the .38Spec, will start to suffer in the 2" barrel.

Even your fast burn target powder load has a 11.2% velocity increase in the 4" over the 2", which means a 25% energy gain( mv2/2G),.... which is the hammer that drives the nail home remember. I agree with your findings however,... that most handgun rounds suffer far less from barrel chop than in-efficient, over-bore rifle cartridges do.

Seeing you have a chrony all set up for you, it would be nice to see full power .38 loads in the same guns. Even a 6" put in would be great for comparison. I guess heavy +P or +P+ loads are out of the question in the guns mentioned.

IIRC, a .38 Special 158gr standard velocity,..a duty police revolver load of yesteryear, was unable to penetrate a drivers side window in a 1970's sedan when fired from 6 feet in a 2" chiefs special 50% of the time.The standard 4" barrel S&W M&P model10, was 100% effective in penetrating and would hurt anyone on the other side for sure.

 

[Ganderite]

I might repeat this with some factory 158 lead and some 158 handloads.