I have an MP5K PDW and I basically did the same thing, minus the metal body (maybe later.. hehe). I got an MP5A4 (229mm tightbore vs. 141mm makes a difference) inner barrel with a silencer, but no 9.6v battery for me. I think it looks awesome with the RAS, but that makes it doubly a pain in the ass to change or even charge the battery. I didn't know you could get a PDW stock with a battery in it...
I ended up getting a claw mount so I wouldn't have to remove my sight, then the RAS as well to remove the battery, but if I had stuck with the RAS, I would have gotten an MP7 style folding foregrip like
this one.
Nice MP5K btw
