It is interesting to see that my picture of the Beretta 391 trigger group parts is so highly regarded that it is being copied all over the internet. Technically, it is copyrighted, but I won't give you any trouble over it. I do wish people who copy and use it would give me credit for it.
That picture is used in one of my posts on shotgunworld.com and also in my book on disassembly of Beretta semiautomatics - See http://www.shotgunworld.com/bbs/viewtopic.php?f=73&t=123733
BTW, trigger group parts for the 391 are readily available, and most of them interchange with parts for all the other 300-series models (some parts are different in the 302).