If so, you might want to read this:
Ruger recalling some MkIV (including 22/45) pistols due to issues with safeties.
Seems that if you put the safety on part-way and then pull the trigger (why??) and then move the safety, than things get all loud and such.
Mine did not exhibit this malfunction, but it was in the recall SN range so I sent it back to err on the safe side. After I got it back "fixed" it would then act the way the recall was supposed to correct. Press trigger with safety on, then disengage safety and then even look hard at the trigger and it would fire.
So I replaced the internals with Volquartsen bits and now it's all groovy.