"I wanna introduce you to a personal friend of mine. This is an M-41A pulse rifle. Ten millimeter with over-and-under thirty millimeter pump-action grenade launcher."
-Corporal Dwayne Hicks
This is a one-to-one scale (or close to it) model of an M-41A pulse rifle from the movie Aliens (1986), recreated from photos I found online. The only thing that actually moves is the trigger.
I use a lot of SNOT construction for it. Notably, there is not a single piece in it with the studs pointing upwards, not even on the inside (unless I'm forgetting something). The majority of the structure was constructed studs-down, just because the black slopes I had when I built it were better suited to that. I started with the grenade launcher pump handle at the front.
Here's the front. The tire sticking out in the middle should probably be a hollow barrel for grenades to come ot of, but this was the best I could do to get the size and shape I wanted (don't ask me why I didn't turn the tire the other way, because I can't remember any more--maybe it wouldn't fit).
This angle shows another flaw that I didn't know about when I built it because none of the photos I used showed this angle: the gray part should have a deep groove all the way along the top of it, presumably to use as a sight. I'm actually glad I didn't know, because I don't think I would have been able to reproduce it without making the top part extremely weak.
This picture is similar to the first, but I'll take this moment to comment on another detail. The bottom of the gray part detaches cleanly the way I built it. It's appropriate because it would be the bottom of the clip. There's no room for an actual clip in mine, though.
Here's a comparison with one of the photos I used. Note that the comparison one is at more of an angle than mine.
I don't think the molded part was quite so brown in the movie. I would have made it dark gray if I had enough. I made it before the Star Wars sets came out, when dark gray was hard to come by.
Here's another comparison. Notice I even included the electronic bullet-counter. Mine always has 11 bullets in it. I put the counter on both sides (the side of the rifle that I haven't shown you is pretty much identical to this side except for the little knob a few inches up from the trigger). I'm not sure if the counter should be on both sides, but I'll shoot you if you complain. And then I'll still have 11 bullets left.