Disappointed - Aero Precision AR15 Carbine Buffer Kit

I purchased two Aero Precision Gen2 uppers and lowers for a very good price. Was excited when I found this kit!! That was until I tried installing it. There are not enough threads on the tube. The tube has to be screwed in so far to keep the buffer retainer in place that installing the rear take down detent spring is extremely difficult. If you use a 4x40 set screw to retain the detent spring then it's not too hard but installing that small set screw is a difficult task in and of itself.