does anyone have any problems with their rifle short-cycling? (Disallowing bolt from fully cycling)  I thought it could possibly be from ammunition, however, my other upper cycles the ammo fine.  Might anyone have any input on this issue??  Thanks for your advice, in advance.   Dan

This can happen if you limp wrist the weapon - try a firmer grip and if that doesn't work, the gas port will need to open up a bit.  
HFG

Also take a look at this thread, there's some good info on getting a short barrel to run well.

www.arfcom.com/forums/topic.html?b=3&f=14&t=153425

11.5 here for an awful long time.   Had to open the port when barrel was new (too small)...

inspect gas key for flat mating surface and those 2 small screws being tight, then "stake" the crap out of them.

Place 1 round in a mag, mag into gun, and load,,,,, discharge the round.  Did the bolt lock open on the empty mag?  Do this a couple of times.  If lock open, all should be fine.  If no lock open, look for port mis-align to sight base, or port being too small....  .080-.086 is typically the magic nummber on the gas port.

I've encountered the same problem!

First, go to the troubleshooting forum. Tweak has several threads in the FAQ that will allow you to systematically check your malfunction on a step-by-step basis. You'll save a whole bunch of time if you follow the directions.

Second, unless you're shooting M193, Q3131A, M855 or equivalent factory ammo you can't rule out your ammo just because it runs in another upper.

Third, is this a new barrel installation? Everything else checks ok? Polish your chamber!

tagged

New 11.5" Bushy bbl, RRA flattop upper, Bushy Gas tube, Bushy bolt carrier group.  I haven't tried different ammo.  I'll give each of your methods a try.  Thanks for your input.  I'll let ya know.   -Dan