I hate when that happens
 

I just bought a HK tactical USP .45 so I could mount a knight suppressor on it. Well, the second day I shot it I didn't tighten the can down at all so first round.. BOOM!. The can went flying and landed 8 feet down the range. I've never more embarrassed in my life. My question to you guys is did I damage the pistol or the suppressor. After that incident, it seemed my groups went from 1 moa at 30 feet to maybe a little more. I was shaken up for awhile after that then started to get angry at being so irresponsible.

Your groups have probably opened up because you're scared. Relax and breathe, they'll come back down.

Get the pistol and can to a qualified gunsmith for inspection before shooting it anymore though. Better safe than sorry.

Absolutely!
 

mattg just gave you the best advice you will ever get about a firearm!

Have it professionally checked BEFORE you fire another round!

:)

Yeah, that's the first thing I did. I bought them of the range so the owner was more happy to look at the pistol and supressor and fired a couple of times. Thanks for the advice!

If a qualified smith has given the pistol a clean bill of health, then the best thing you can do to get the groups back down is to shoot.