A mp5sd is ALOT more expensive than a regular plus the additional tax and can... generally. A friend of mine has that set up and while nice I prefer the standard mp-5 and an aftermarket can. I wish I would have got into the class 3 world before verything went nutz... it is absolute BS that we can not buy new mg's for the price of new. The collector nature of the game is unreal at this point on the MG's. There are several systems out there fore can attatchment. Gemtech makes one... Semi auto's can have slide locks fitted to "lock" the slide and eliminate that part of the equation. Bullet slap- or the noise of the bullet hitting the target can be quite load and if close confuse the unknowledgable with firing noise. It is really an interesting hobby. No where near as "evil" as some would have you believe.