I have this kit installed in my Preban Bushmaster CAR-15. I purchased it from www.armforte.com. I was reluctant at first but after speaking to Mack Gwinn at length about it I decided to try it out.
The kit itself was very easy to install with the exception of the gas port mod. which was done by GG&G when they were installing my Front Flip Sight.***
I have since but almost 2,500rds through the rifle with 400 being a "Beta drum torture test" The rifle emptied the drum 4x in a row with no fail to feeds, stoppages or hiccups all in rapid fire. Yes, The rifle was allowed to cool in between reloading the drum. I was convinced that after inspection when nothing was damaged inside the rifle, that I could recommend this kit with a Clean bill of health.
The system makes it almost impossible for the bolt not to seat, aids extraction and was worth what I paid. It did not effect accuracy of the rifle at all. It is removable and it did seem to help keep rounds on target, during what seemed to on-lookers as a blatant waste of ammo.
Tom from SUBGUNS.com did not like the kit, and had stated that his broke after very few rounds.
I respect the man's opinion but I believe that he might have installed the kit incorrectly or damaged it during installation. I don't see any other way that it could have broke so quickly.
JerrY
***It should be noted that Bushmaster does not finish the barrel before the gas block is installed. This means that when the guys at GG&G installed my F.F.S they also had to re-finish the upper due to gas block being used by Bushmaster was larger than the F.F.S leaving a portion of bare steel on the barrel. Not really important but it comes to mind.