Seen and read numerous tests over the years...Most enlightening one was where they took a heavy barrelled .308, started with a 26" barrel, and then shortened and recrowned it 2' at a time, down to 18" (5 different lengths).
They were losing about 150 fps for each 2" of barrel removed. (Side note: accuracy remained unchanged).
This lines up pretty well with other things I've read and heard, that say something like 50-75 fps per inch of barrel length. Variables include cartridge (duh), powder burn rates and bullet type.
I suspect that, if you handload, you could minimize the effect using a relatively fast powder, for more "burn" in the shorter barrel. Would be an interesting experiment
"If you Listen to Fools, the Mob Rules"
"No one has the answer, but one thing is true.
You'e got to turn on evil, when its coming after you.
You've gotta face it down,and when it tries to hide,
you've got to go in after it, and never be denied.
Time is running out...Let's roll.
Let's roll for freedom, let's roll for love.
We're going after satan, on the wings of a dove.
Let's roll for freedom, let's roll for truth.
Let's not let our children grow up fearful in their youth."