18" or 20" barrel for .308?

[Pappabear]

yup, same deal. I run a 16inch on my LMT MWS, it gets to a 1,000. Not easy, but it can get there. 20 would be better.

Just depends on what you want it to do. I would like to run a can on 16inch and put a 20 inch SS barrel. But the barrels cost too much IMO.

[Abraxas]

Been there done that.


Basically, compute for 15-25fps per inch of barrel loss. Yet some barrels shoot fast, others slow.

Expect 2500-2575fps from an 18"
Expect 2525-2600fps from a 20"

This, given a stout load of varget and a 175SMK.

Does the Hornsbys improve your grouping?

[orkan]

Doesn't seem to. Causes the safety nazi's to lose their ****n minds however.

[Ironman8]

yup, same deal. I run a 16inch on my LMT MWS, it gets to a 1,000. Not easy, but it can get there. 20 would be better.

Just depends on what you want it to do. I would like to run a can on 16inch and put a 20 inch SS barrel. But the barrels cost too much IMO.

Wouldn't the suppressor on the 16" make it perform just as well as the 18" (unsuppressed) with the added bit of velocity that you'll pick up with the can?

[AR15barrels]

Does that 10-20 FPS per inch rule apply to gas guns as well?

It applies to any gun, bolt action, pump action, lever action or self-loading.
The FPS lost or gained per inch is NOT a linear function though.

So, you might lose 10-20fps when going from 26" top 25", but the loss from 17" to 16" will be significantly more.
This is a function of barrel pressure and time.
The faster a bullet is moving, the faster it moves down the barrel one inch and therefore the less velocity you would lose.
Also, the lower the pressure, the less velocity that is getting imparted per inch of travel.
The greater pressure in the shoorter barrel is imparting more velocity per inch of travel.
So, as a barrel gets shorter, the bullets are going slower at the muzzle and the velocity loss per inch will be greater.

[AR15barrels]

Wouldn't the suppressor on the 16" make it perform just as well as the 18" (unsuppressed) with the added bit of velocity that you'll pick up with the can?

Yes.
This is a problem for people without suppressors though.

The short suppressed barrel people argue their barrel length performance without considering the performance boost of the can.
Then the people who don't have cans use those statements as gospel.
I site franks video's use by everyone as evidence...

[Cesiumsponge]

I went with a 20" for my rig...only because 26" was the only other factory option. Handling is more important to me and it cancels out some of the additional weight created by a can (once my Form 4 clears)

I don't have any convenient 1000+ yard ranges near me but 20 mils is enough to play, even if it stacks the deck against me when competing with folks doing it with 24 or 26" barrels. I simply don't do enough of that type of shooting where the additional accuracy outweighs a shorter barrel. 20" seems to be a good compromise between the 24-26" crowd and the 16-18" crowd.