I'm not sure of the barrel length... I put a longer one in my K but not quite that long. Mine still rocks for CQC though...
I basically did the same thing here but covered the barrel with a silencer and got some after market internals for durability / slight RoF upgrade. Top is off with a claw mount and an rds. I should take some pics and put 'em up
The thing isn't half bad outdoors either. It's made a few people eat their words about small guns outdoors on more than one occasion
