02-03-2012, 03:27 PM
hm2 clark Wrote:(1) On our old forum (before it got eaten) an engineer type showed pretty convincenly that for every inch of increase barrel length BETWEEN 10 and 14 inches you get an additonal 50fps. For every inch between 14 and 18 maybe an additional 25fps. and every inch after 20 inche maybe only 15fps increase. Most of us stay in the 18-20 inch range unless we plan to shoot waayy out there.
I haven't found that to be the case. I have a 20 inch barrel and the guys with 24 inchers get 100 to 120 fps higher than I do with the same load and 120/123 grain bullets. That's using AA2520 powder or ones in that range.
For example I get about 2520 fps with Hornady 123 AMaxes and 30.5 grains of AA2520. Guys with 24 inch barrel get about 2650 out of it. I get about 2510 fps with the Hornady factory 123 AMax loads and they claim 2650 on the box (24 inch barrel, I presume).
I don't have any experience on longer than 24 inches, or shorter than 20.
The Alexander Arms ballistic tables hold true for the rounds and barrel lengths I've tried, at least in muzzle velocity. http://alexanderarms.com/images/pdfs/gre...istics.pdf
RR