Home Forums Reloading Big Game Rifles Specific 7mm-08 question

I am considering having a 7mm-08 built and am curious as to the loss of velocity going from a 20" to an 18" barrel. I don't think its significant but would like to hear the thoughts of others. Thanks.

I bet it would lose less than 100fps. Plenty of good powder combos nowadays that will allow you to gain some of that back, IMO.

Thanks JG. I appreciate your input and was thinking much the same as you.

20” is my threshold for loudness. 18” seems tougher in the 7mm-08. A buddy has had an 18” model for 30 years as his main rifle. He now has tinnitus. 18” with a can would be another matter.

The Berger manual states expect approximately 21FPS per inch of barrel from a 24"

Good luck and shoot straight y'all

If their tinnitus is caused by this his hearing issues would stem from his failure to wear hearing protection while shooting rather than the length of a barrel.

I'd not argue with that logic, although 30 years of hunting exposure with the short barrel might be his problem. He wears ear protection at the range.

I shoot supressed for what it’s worth...

From what I've seen with 7mm-08 loads in 18 and 20 inch lengths, you'd be looking at maybe 50-80fps loss going 18 vs 20, depending on the load.

20" fo sho.
Big Ed

All calibers and loads vary, but 20-30 FPS per inch lost is what I use as a base line. View this link, closet test is the 6.5 Creed.
https://matchgrademachine.com/velocity-testing-thompson-center-barrels/

Thank you.

FWIW, my boys‘ youth model with 18” tube shoots 2725fps with Remington 140 corelocts. I didn’t expect it to hit 2700. I can’t say I noticed it being Any louder than my other big game rifles.

Good information. Thanks to all.

Cliff, you didn't mention bullet weight....or powders potentially to be used...

with a faster powder, such as 3031... and using bullets between 120s to 140s..

I'm going to speculate that you wouldn't lose as much velocity, gaining full pressure quicker...
and also wondering if it would less muzzle blast increase, than say the same bullet using say 4350 or 4831...

just speculation on my part... ain't going to cut down a barrel to test it...

but maybe JB or someone with his experience and credentials can either verify the thought, or point out what an idiotic idea
that is...

if a short barrel length Model 7, fell into my lap... 3031 would be the first powder I'd reach for...

it sure worked well in a 7 x 57 I have....

I know you have your reasons for wanting to shorten it the barrel. But whatever the reason, I’m gonna argue against doing so. I personally have two 7mm-08’s and both have 22 inch barrels and I’m perfectly happy. I’ve never seen the need for anything longer or shorter. I get over 3000 fps with 120 gr bullets, and over 2800 fps with 140’s and that’s all I shoot. None of those bullets are loaded to maximum. I’ve never had a handling problem with the 22” barrel length and get velocity that will get the job done at any distance that I intend to shoot at game. But, with respect to you, to each his own.

Like lastround says above, I agree with him from experience. I have 2 7mm08s, one with a 20" and one with a 24". My 20" bbl is handy no doubt but to tell the truth that extra 4" of barrel is really not that noticeable in the field. I'm in the process of haveing another 708 built and its going to wear a 22' bbl. The 20" one is going to my daughterinlaw.

the information provided here by many has given me reason to rethink my thoughts and I'm putting this idea on hold.

Of all the cartridges I have chronographed over the (almost) 40 years, the 7mm-08 seems to be the least affected by bbl length--at least in the 18 1/2", 20" and 22" bbl lengths I've chron'd.

Back in the 80's their was an article each in Shooting Times and Guns & Ammo where the authors started cutting down the bbls in 2" increments of 7mm-08's and chronographing them. IIRC one was 24", the other was 22". I don't think there was 25-30 fps velocity loos from the longest to the shortest length.