Wow very cool, thanks for the link! It's nice to see one of the original blasters at all angles in such clear photos/video. Beautiful indeed..:love
I think it might have had to do with filming location why the real Mauser wasn't used in ESB, but I'm not sure on that.
When it comes to the blank firing through, I don't think they made use of the Hero DL-44's blank firing abilities in ANH or ROTJ at all. The muzzle flash in ANH is blue and likely added in at some point (possibly SE releases), plus we never see the hammer pulled back or the bolt fly back indicating it was fired during filming.
I guess I would be afraid to fire it too with all those parts on there..:lol
-Carson