My gunsmith engineered a M16/9 Beta Mag tower. This would be for all Colt style uppers (not for Olympic Arms). It's based on an Uzi mag so unlike the plastic Beta tower it should last forever. It will include the tower and two extra dummy rounds.
Tested full auto in my M16 with a Colt one piece magwell adapter and a Hahn drop in. Runs flawlessly FA. Taking orders for the next production run.
Price is $93.85 delivered via priority mail. Paypal accepted add 3%.