To the MK2, its doesn't.

As Mr Harris said, the std. thing is really a muzzle weight.

One option would be to ounterbore it and have it threaded 1/2" UNF female, then either fit a 1/2" male silencer, use use a male-male adapter. I've seen this done on an SR (Mk2) and it worked well - just stick with a small silencer, e.g. manders. Makes the gun look a bit long though.