Thread: Barrel chop

A loss of 200fps going from 24" to 20" doesnt add up with the .308, you should theoretically have lost around 100-120fps at most.

My suggestion would be that theres an error somewhere with either chronograph or loading. 44gr is a pretty light load to be doing 2820fps with a 150gr so may be as simple as a chronograph error, or those loads were hotter than 44gr.

End of the day its still going to do the job perfectly fine at the distances you indicate your going to hunt at, but you are right in thinking a loss of 200fps is abnormal. Velocity loss vs barrel length is not a linear thing, it is a curve that ramps up at the beginning of the barrel and then flattens off as the barrel length increases. Cartridge type / bore size / powder used all effect the shape of this curve and therefore how much velocity is lost when shortening can never be a set "x fps for y inches". Due to the shape of the curve, the overall length plays a big part too. For instance with a .308, going from 28 inches to 24 will lose you just under 100fps, however if you were to shorten a barrel that was 18" to 14", you would lose close to 200fps.