Quoted: The same load in my 24 inch 1:8 twist barrel is usually about 200FPS faster than in my 20 inch 1:8 twist barrel.
|
Sig-
Your experience is on the high side of what I have seen.
It sounds like your 20" barrel is a slow one or maybe your 24" barrel is a fast one.
Adding the differences between different barrels up could certainly make up 200fps difference over the 4" additional length.
75fps to 150fps difference between 20" and 24" barrels is a commonly quoted difference.
My research below seems to prove this out as well.
Just for fun, I ran a quick series in Quickload to see the effects of barrel length.
My example is using a 55gr Nosler ballistic tip and 27.5gr of Win 748.
Quickload predicts 3218fps with a 20" barrel and 3352 with a 24" barrel.
The difference would be 134fps.