We took a Broughton 5C with 1 twist in 11 inches and a groove diameter of .3077" that was extra long, and made two barrels out of it, one was 11 inches, and the other was 25 inches in length. We shot Hornady 110 Tap and handloads with the Hornady 110 and measured the velocity difference of a number of different powders with the Oehler. Data to follow....

sounds like an interesting comparison

keep us posted

Hornady 110Vmax TAP was running just shy of 3500fps out of my 26" Broughton 5C (w/ suppressor). Stopped testing due to faulty primers (piercing).

110Vmax over 48.7gr Benchmark in Winchester brass ran about 3425fps.

Powder 11 inch 25 inch

Any update to this? I'd be curious to see what that 110 V Max was leaving the 11" barrel at.

ETA:
While we're on the subject, you wouldn't happen to have velocity data for various commerical or military loads out of various .308 AR barrel lengths, would you?

I've found a little data here and there, but would like to see what one particular load does (say M118LR or 155 TAP) as you chop the barrel down a couple inches at a time (say 20 inches, 16 inches, 14 inches, etc).

Basically, at what point do you decide that you've neutered the .308 barrel enough that it's no longer superior to an M4 with TAP or Mk262?

When I get time, I will post all the data. The bottom line is this, same load same powder, the 110 VMax bullets lost between 520 fps. and 565 fps when shortening the barrel from 25" to 11 inches.