Shorter barrel 5.65 AR loads

[nelsonal]

Does anyone have any info on loads worked up for AR pistols or short barreled rifles? It seems like the fireball/noice could be reduced without giving up too much velocity if loads were worked down from the loads that were optimized in longer barrels.

When I look at the pistol comparisons (I realize the ballistics are different for rifle barrels) it seems like there are huge drop offs in velocity begin somewhere in the 5"-7" for most rounds. I'd guess that rifle rounds have that drop off at longer lengths, but it seems like rounds could be optimized for the shorter barrels, however I've never seen info about anyone doing this.

 

[Walkalong]

To stop the fireball, you would have to lose a great deal of velocity.

 

[wanderinwalker]

Maximum performance will only come from burning maximum amounts of the slowest practical propellants you can stuff into a case. Unfortunately, this means fireballs and noise when shooting rifle rounds in shorter barrels.

I've never truly understood the "optimize powder" for short-barrel loads. (Primarily applied to short Magnum caliber handguns as I normally see.) Sure, using less of a faster powder will reduce the flash and blast, yes, no question. But maximum speeds will still come from burning more, slower powder (please see first sentence).

And I use "slowest practical" because while I can put 4350 into a .223 case, it's too slow to be useful (just as you can burn 4895 in a .44 case if you so desired, I guess). Every cartridge has a slowest-practical powder range that will work, and from what I can see these are where top velocity is normally found.