Longer barrels 300 AAC BLACKOUT

[rsilvers]

So this is kind of interesting. Even I was wondering what happens when the barrel gets to 20 inches. Some have said 300 AAC BLACKOUT would not be so good from longer barrels, but that is not the case.

http://www.m4carbine.net/showthread.php?t=65866

I noticed that the very smokin' hot Hornady 75 NATO Superformance load is 75 grains at 2909 fps from a 20 inch barrel. That is 1409 ft-lbs.

With Remington 155 ammo I got 2100 fps average 10 shots in the 20 inch barrel. That is 1518 ft-lbs.

So in a 20 inch, 6.8 will beat 300 AAC BLACKOUT for energy, but it still exceeds the very latest and hottest 75 grain load in 5.56mm NATO.

This is for a 110 grain bullet:

http://img607.imageshack.us/img607/7426/300blk.jpg

My take is that barrels up to 20 inches make sense for general use, and longer barrels make sense for more limited use.

[i8asquirrel]

That is good info, I however am looking for mainly subsonic use...In my case longer than 16" make no difference except adding weight..I think that somebody looking for a low recoiling rifle for new deer hunters would be well served with a 18 or 20" rifle in this calliber!