First off...for those of you new to Airsoft Society. Let me say this first off. American Consumerism Does NOT apply in Airsoft. This thread has been create to help those of you suffering with the "odd" tolerance issues with EF G17 in Gen 3 and Gen 4 Here are some videos of them working - AFTER Hand Fitting: Slide was binding on outer barrel with this unit. I "Hand fitted" this unit and now it's working. This is the comment from another user: New message from: da_469169 (0) There's another company called gas blowback central that makes a threaded outer barrelnfot ef gen 4 glock 17s but only issue is that it has the same design problem as the pro arms. I like the ef glocks, only downside is the little support it has. But I am looking forward to the ghk glock 17 gen 3 since they're working with umarex so its also a liscensed product and will definitely have more support than the elite force glocks. My comment Geez...thanks Umarex/Elite Force.... da_469169 says: Yeah mine has that nub. My comment Wow...are tolerances that varying from unit to unit? You have the Anti-cant nub too on that Gen 3? da_469169 says: Another thing I wanted to add, is that the tm barrel that I also bought works fine with the stock hop up for the gen 3, didnt have to sand down the nub however it is a little more stiffer if I use the maple leaf hop up. I bought my glocks this year.