I sold my two primary guns to build a LH Tikka. Bought the tikka yesterday. As It sets its a .308 with a 22.xx" barrel. Using my wife's 7-08 now with the the same barrel length. I hate it. I got used to the 20-19" rifles I was using.

How much would I lose cutting it to 18" on the new .308. 100-150fps? If that's all that's fine. Less whip and more maneuverable is what I'm looking for.

Will later change the bolt stop and mag and rebarrel to 6.5-06 at 20" but fo now going to cut this beast down.

Rule of thumb is typically 50fps per inch.

Had my tikka 6.5x55 cut to 16.25.
Going to range soon to find out how it does

You sure about the number?

I'm thinking/hoping 25'

That's what I've always been told.

My experince with 308 is closer to 20

Yes. And 7-08, and the short action 6.5's

Typically, you lose about 15-20 fps per inch, which will be the case for a 308 shooting the 150 to 180 grain bullets. But it depends on what the caliber is and how light of a bullet. If you are running a magnum round with a very light bullet that's running 3500 fps, you will lose/gain more, for obvious reasons. But with your common calibers and bullet weights, it's about 20 fps per inch.



^^^ That's incorrect.

I always say 50 or less there are too may variables to guarantee one or the other.

This one is 18" and I'm getting 2600fps w/ a 175smk

I have 3 .308s, barrel lengths are 24", 22" and 18 1/2". Forget the 50 fps/inch, I have not seen that to be the case. With two different 165 grain loads, I measured the difference in velocity between the 24 and the 18.5 to be exactly 168 fps-- and that is a difference of five and half inches.

If I followed you correctly, you're going from 22" to 18"? I wouldn't worry about it. Sight it in, hunt with it, and don't think another thing about it if the accuracy suits you. I have killed a bunch of deer over the years with my Rem 788 with an 18.5" barrel.


Rick

That figures to be about 30 fps per inch of barrel. Chad has seen 20 fps per inch of barrel for .308, typically. That just shows that all barrels are different and you can't nail it down, only come up with an approximation. The cartridge makes a difference also.

I shoot 168gr AMax from Chad and it is chrono'd by him at 2630fps out of his 22" barrel and chrono'd at 2490-2510 out of my 16" barrel. This is a lose of about 23 +\- a few fps per inch. My 16" barrel still stabilized the bullet out to 800 yards for sure probably further just haven't had a chance to shoot further than that. I'd never own a long barreled 308 again lol no use in it.

You can easily get velocity variation from the same length barrel in 2 different rifles with the same load. So, it's not a 100% accurate method to know exactly what the difference is when using different rifles, especially with different 165 grain loads.

more things to discuss..
Bullet weight? Do you guys think lighter or heavier bullets work better in shorter barrel lengths ?
Part of me thinks heavier bullets would be better due to slightly longer dwell time allowing more pressure to be built up.
What about power types?
Barrel twist rate (1 in 10 say 1 in 12)

What about 7mm08 vs 308?
I would think the 308 would be a tad better due to the larger bore diameter creating a bigger expansion chamber.

^^^ That's the debate! Too many items to go over, to really figure it out. If you go short, I personally like the heavier bullets.

I have only shot one deer, a doe at about a 100 yards with my 16" 308 using factory Barnes 150TTSX.
The little project Weatherby stacks them in the same hole and so I haven't messed with anything else.
But it dropped in it's tracks with a double lung and jacked it up internally.

My 20" I have settled on 178 AMAX for everything from game to long range.

I have toyed with the idea of a short, 16-18" 7mm08 but I bet I don't see any real world benefit over a 308 out of a shorter barrel.
My experience has been that high BC bullets don't trump speed until you get past 4-500 yards.

A lot depends on the cartridge and rifle when trying to nail down how much is lost per inch on average. There are guesses and that is about all the fps per inch will be unless you check velocity cut an inch off then measure then keep at it until shortest barrel length is found. That works for that load but still might yield different results for a different load and rifle.

Over bore cartridges will loose more per inch than more efficient ones. Cartridges like 264 Win Mag, 257 Wby will both loose more fps/inch than say 6.5 Grendel or 257 Roberts.

The longer the barrel the less fps will be lost per inch being removed will make. Not sure if that makes sense but for instance for the 308 you will loose fewer fps/inch say between a 26 inch barrel and a 22 inch barrel than a 22 inch barrel and an 18 inch barrel even though there are 4 inches difference in barrel length.

Take for instance the 308 family. 243, 260, 7mm08, 308, 338 and 358. As the bullet diameter increases the less fps will be lost.

Generally there is no one number that will fit all

"Take for instance the 308 family. 243, 260, 7mm08, 308, 338 and 358. As the bullet diameter increases the less fps will be lost"

Agreed.. I see far more shortie 16-18 308s than the others..

If you dial for elevation and are mainly interested in hunting under 500 I don't think it really matters much.
If you want to have a MPBR of say 300 yards and dead hold into the vitals then the faster/flatter shooting calibers will be better of course.
But to be really effective speed helps flatten that load out and I think trumps high BC bullets moving slower (which buck the wind better at distance)

I have a 788 in 7mm-08 with a 18.5 inch barrel that runs 200+ fps slower than the 700 in the same caliber with a 22 inch barrel, does that mean that every rifle will have over 50fps per inch difference in that caliber? NO. Rifles and barrels are not all equal. Loaded for 2 different 7mmSTWs for a while same model and barrel length, one was always 200+ fps faster than the other.

I believe that inside 300 yards BC does not make much difference, run the numbers in a calculator and it just isn't much difference. Get past 300 and the higher BC bullets will start to have a real advantage especially with bullets of the same weight. If going further than 300 I prefer high BC bullets which are usually the heavier ones

I agree 100%
Some barrels are just faster than others.. my LTR 308 is a slow, but amazingly accurate and consistent barrel.

I run 178 AMAX out of my 20" 308 and they get moved so much less in the wind at 500 than 168s and are much more consistent out to 1K

unless you're planning on shooting stuff at 800-1000 yards with this gun, is it really going to make much of a difference how much you lose in the real world?

If that is directed at the OP I would agree 100%

True, that. This was just for my own curiosity's sake, just to see what the difference would be. One load was my pet load of 3031, the other the load of 760 that I first settled on back in 1981, both loads straight from the Speer book, so no "freelancing". I had expected to see maybe a bigger difference with the slower powder, but the 10 shot averages turned out to have the exact same differences- with those two guns and those two loads. That surprised me. And yes, not 100% accurate, but neither is the Rule Of Thumb we've all read for so long. I just wanted to see what it was doing.

Mostly what I was getting at though, was the 165 Speer BTSP/760 load killed over 20 deer with authority out of that short barrel for years before I ever broke down and bought a chronograph. The almost 200 fps I was losing over Speer's listed velocity made absolutely no difference in the field that I have ever seen. Granted, I'm not shooting at 400 yds so the difference in trajectory did not come into play, but at shots from 25 to 278 yards over the years, only one bullet did not completely exit- so I don't think I left anything on the table at all with the short barrel. The deer certainly never have known the difference! The Alabama 8 point over my fireplace right now would agree, if he could- he was taken with that load


Rick