308 velocity vs barrel length


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cidirkona
January 30, 2006, 08:56 PM
I've looked around the net and searched the forums, but can't find an easy chart to look up .308 velocity versus barrel lengh... more specifically...

What are the velocities for the different DPMS 308s with only barrel length being the varying factor? A link to a webpage (which I can't seem to find) would be an ok answer too! :)

-Colin

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Roudy
January 30, 2006, 10:40 PM
A few years ago Guns & Ammo had an article about testing the velocity loss due to shortening the barrel length. They started with a 26 inch barrel, fired several rounds and measured the velocity, then cut off an inch and did it all over again. They kept repeating until they got down to 16 inches I think.

My memory is probably not all it used to be, but I think that the velocity loss varied a bit from one stage to the next the upshot was about 100 - 200 FPS per inch of barrel.

I suspect that the use of powders with different burn rates would have an impact and the velocity could actually increase in some instances.....IE: very fast powder and very long barrrel VS very fast powder and shorter barrel could show an increase in velocity with the shorter barrel.

If you haven't tried the gun magazine web sites that may be a place to find what you are looking for.

Fumbler
January 30, 2006, 11:04 PM
Generally with lengths between 20 and 26 inches you lose about 40 fps per inch.

When you get into really short barrels you start to lose a little more per inch, about 50fps.

It's hard to say for sure because, like Roudy said, of the different powder burn rates. Also, barrels from different manufacturers will shoot differeent velocities with the same ammo even if they are the same length.

P0832177
January 31, 2006, 10:21 AM
Here is good example! Some barrels are very different. Case in point. I have 22" Mike Rock 1-11 twist barrel chambered in 308. I get the same velocity from BHA 168 gr match ammo that I did with the 26" VS factory barrel.
There is no way to quantify the velocity loss with a gun, in general terms perhaps!

cidirkona
January 31, 2006, 10:34 AM
It's comparing Apples and Volkswagens then?

What approximate velocities should I be expecting out of a 308 dpms panther in 16 or 18?

-Colin

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