Kleen bore accu-wedge: it works, sort of... - Kleen Bore Accu-Wedge AR-15/M16 Buffer System

The Accu-Wedge does not "eliminate" play between AR uppers and lowers (depending on the severity) nor is it a drop in modification. I had to trim the part in order to get it to work in an M&P 15. The play between the upper and lower has been reduced, but assembly and takedown require a lot of effort and care, meaning physical strength, ensuring that the wedge is properly in place, and more importantly, time: It takes at least a minute to reassemble the rifle. *Bottom line: it's a good fix for recreational shooters, if your safety/life may depend on your rifle, take a pass.
Pros: Reduces "slop"
Cons: Requires modification, relatively expensive

This review was written in the old system and had content requirements that are different than reviews written today.