Barrel length issue - Rifle Shooter Mag

[No Fear in Accuracy]

Hello,

I was reading the Rifle Shooter, Sept/Oct 2003 and there was a discussion about the "Barrel Length vs. Velocity". See pg. 60.
I noticed on page 62, they did experiment with H-870 powder on 300 RUM, 220gr bullet.
They tested between 22 inch and 27 inch and the velocity doesn't drop as much as it should.
I was planning to get 36 inch barrel in 2004 and I'll be using H-870 for 338 Tomahawk (neck up to 338 from 300 RUM and blown out shoulder).
I wondered if you use H-870, very slow burning powder, adding two inch on the barrel will make a big difference? I wish to say it will increase 50-100 fps every two inch increase. According to this magazine, the velocity doesn't increase a lot. I specifically talked about H-870 powder with long barrel.
27" - 3,107 fps
26" - 3,088 fps
24" - 3,046 fps
22" - 2,997 fps

Hmm?

-Denny

 

[Darryl Cassel]

Denny

Usually you will find a 25 to 35 Fps increase per inch of additional barrel length, up to 36 to 37".


Later
DC

 

[Michael Eichele]

Barrel length and velocity isnt always what it seems. Example in my 308s I get 20 FPS difference per inch. I have a 24" and a 26" barrel, 20 FPS is only safe velocity difference. Now I shoot the 26" er with a 175 at 2750 FPS, accuratly

, The 24" er is capable of 2700 FPS safley, the flip side is with the 2" shorter the muzzle pressure and blast is increased to the point it smacks the crap out of the bullet as it leaves the muzzle and wont shoot a group under 1"-1.5" I then have to reduce the loads to 2550 to acheive the same .250 groups I get from the 26"er. A muzzle brake solves this problem, but then that just adds 2"more and I might as well have it in barrel vs a brake