The ray gun's design was, at the time, wholly original; its angular fins and concentric circles made it look almost like a space ship. It was one of the larger space guns, and its die-cast construction lent it a nice heft. I can only imagine how fun it must have been to play with it as a kid. (Though I can say with authority that playing with it as an adult is a helluva lot of fun.)
I've always liked this toy's paint scheme. The whole thing is done in red, and then silver is applied by an air brush to highlight the gun's contours. It's a nice effect, and one I've never seen on any other toy from that period. (It was also released in blue with silver accents.)
The Space Pistol fired rolls of paper caps, which were loaded underneath the top sight. Smoke exited the front of the barrel.
Lone Star would go on to reuse the gun's design a couple different times, and there's at least one plastic version that came out of Hong Kong in the late Sixties.