Just wanted to inform the piston hive... if you intend on building an AR pistol you cannot use barrels by Franklin Armory with the AA pistol-conversion.  They make a nice piece, but they are on the short side of the pistol-length gas standards, and the AA pistol-length systems are a bit longer.  This causes the bolt to not be able to go into battery when the gas block is place to the gas block back shoulder of the barrel.  The drive rod is jammed against the gas block and holds the BCG out of battery about an 1/8th inch.  Forced me to buy a new barrel that I got measurements of first to make sure it's gtg.  

I don't know about Franklin's other gas lengths, they may be fine.  I just got the specs directly from Franklin's tech department and sure enough my barrel was spot on to what they consider in spec, but when I contacted AA they measured their Voodoos they build their pistol uppers with and the distance from the front of the extension flange to the gas block shoulder was about an 1/8 inch longer, (3.66" vs 3.72" avg) so there ya go.  

Ended up buying a new Bergara off the EE.  Guy measured it for me and it was less than 1/32 different than the longest Voodoo barrel AA measured for me, and longer than the other 2 so I should be golden.

I have to commend Aro at AA for getting measurements for me and helping me out with a problem that wasn't AA's.  All the CS guys over there are great, that's why I keep buying their stuff.  I don't have an AR that doesn't have an AA piston on it.

On that note I've got a Franklin Armory 11.5" 300BO pistol barrel with exactly 17 rounds through it if anyone is interested in a DI/Osprey pistol build.

I have got nothing but the most OUTSTANDING Customer Service from Adams Arms!!!  Aro and Cody are Great people!!!