(the first one came with the Bib Fortuna action figure) That's a ski boot lock as the trigger, I see a part from the V8 kit on the back end....and the middle..
The first one is listed in the Visual Dictionary as being an assassin's blaster with short range. Parts of Star Wars.
Coinprop owns (or has owned) one original blaster that he has sold casts of.
The second looks like it could be one of the several strange blasters used by the Rebel Troopers in the trenches on Hoth in ESB. I have not seen this particular one before but I think I have seen the buttstock on another blaster.
My suggestion was pneumatic because they seem to have a smaller chuck, more slender frame, plugs at the base of the handle and weirder hand grip shapes. I'm actually building a blaster off one now (as a custom) and this thing really has that feel to me.
Please... Somebody has to take as many detailed pictures esp. of Dengars and IG88s blaster as possible!!!
The "assasin blaster" looks to be the HERO and not a cast...very interesting.
Dengards blaster features even more of the transcriptor sweeparm parts and a section of the scope rail, that is also used on PondaPabas blaster.