The original 'gun' mic was designed by Harry Olsen for use on the then new 'talkie' films (developed to be able pull the microphone back out of the frame) looked more like a classic sci-fi raygun than a shotgun. It used multiple tubes of varying length arranged in a spiral cluster in front of the microphone element. The later development of using a single slotted or otherwise vented interference tube achieved the same result using a single tube- simpler, more compact, lighter, lest costly- and that was the end of the multiple tube method
Although I've come across them in the past, I can't locate a photo of the original version, built by RCA I assume, as Olsen worked for them and developed the original RCA ribbon mics. I did find a photo of this DIY version which is similar-