Yep, the sonic crack always happens outside the barrel and passed the mod, so there is nothing you can do about it.
I think technically, Silencers are only applicable to sub sonic ammo, after that they are Sound Moderators, although the name seems interchangeable with various manufacturers/retailers/users!!!
Both my .22LR have a SAK on the end, so does my WMR, my HMR has a SM11, and when they dies it will get a SAK as well. The SAK is still one of the cheapest on the market and I'm more than happy with its performance on Sub Sonic and HV!
PS I have heard good things abou