Optimal 0-600 yds Barrel

[biodsl]

My point is simply if you're never operating at less than several thousand foot of elevation you can get way with less velocity than what's needed at sea level.

Also, ballistics change a bit if it's 29 degrees vs. 79 degrees.

If you're willing to tolerate a 1,300 fps speed at 600 yards, you don't need anything more than a 16" barrel, even at sea level in below freezing temperatures. If you need 1,500 in the same situation (sea level at 29 degrees) you need a 20" barrel.

You can play with all this data at JBM Ballistics. Pick your preferred bullet from the drop down menu and then start playing with speeds and atmospheric conditions. http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi