I have an fn 19, and yes, i'd agree, they have a hell of a crack to them!
The scilencer mine came with is crap (i think it is the falcon one but not 100% as i bought the gun S/H), i have just ordered a weihrauch scilencer for mine, tried a logun and a weihrauch one from my uncle and was very impressed!!
getting back to the point though have a look here Falcon Website click on accessories, in the photo on the left is the piece you are drilling number 5? and maybe the scilencer you bought is number 2?
Fraser