Welcome to the forums!
Question 1: I have and SPS Tactical in .308. The reloading manual states that for my particular load, I should be a 2600 fps. out of a 24 inch barrel. I've been trying to find the answer to that myself, on what my velocity would be at 20 inches. From what I've read it's about 40 fps reduction per 2 inches of barrel length. So that would mean it would be around ~2500 fps.
Here's some more info I found at this website: http://www.chuckhawks.com/rifle_barrel.htm
Question 2: here's a pic that shows a caliper on the end of my muzzle.
http://www.wph2005.com/remington/dia.jpg
It's .850 inches at the muzzle.
Hope that helps you out some!
Question 1: I have and SPS Tactical in .308. The reloading manual states that for my particular load, I should be a 2600 fps. out of a 24 inch barrel. I've been trying to find the answer to that myself, on what my velocity would be at 20 inches. From what I've read it's about 40 fps reduction per 2 inches of barrel length. So that would mean it would be around ~2500 fps.
Here's some more info I found at this website: http://www.chuckhawks.com/rifle_barrel.htm
So I don't think the velocity loss is all that much. Some guns might shoot a bitter with a slightly reduce load velocity. It might give you a bit more accuracy!
Question 2: here's a pic that shows a caliper on the end of my muzzle.
http://www.wph2005.com/remington/dia.jpg
It's .850 inches at the muzzle.
Hope that helps you out some!