Not sure if anyone here has an M11/9 but there is a new product about to hit the market that will knock your socks off! Sure you can purchase a Lage upper to slow the rate of fire down or you can have a TASK modification which requires a stock with a buffer tube and a modified bolt. This is a standard bolt that has been augmented with a block of tungsten added to the rear but will work in a stock upper and has had reported ROF in the sub 700 rpm! I have borrowed one of these and will have it at the meet and greet. The guy who designed it has made a deal with the supplier of the tungsten to have a bolt made out of a 95% tungsten alloy which should get the ROF in the sub 600 rpm. He is also working on doing the same thing with a M10 and an M12 in the future. Please comment if you would like additional information. The bolt is a complete drop-in assembly and is guaranteed to work with just about any ammo out there.