Congratulations they are nice full power pistols and I agree mine was loud too.
I have one from the auction site and it worked fine.
https://i.ibb.co/gWt6t6T/20200922-142507.jpg
There's not that much barrel length after the foresight which makes them fragile especially with a long silencer. If you don't mine damaging the painted finish using an adhesive keeps it in place.
If you have a steel set screw you don't want to be torquing it down too tight as it will chew through the softer brass.
With mine cut a peace of thin plastic and put that in the adaptor hole before the screw.