Oh, you could definitely be right. I found the reference without realizing what it was, and beyond that I took some creative leeway. Here's the reference
http://brmovie.com/Images/Things/blaster_02.jpg
According to the website, it is a "Plager Katsumate Series-D Blaster, Model 2019 Chief's Special"
Update with a really impractical holster. Don't even try to analyze how it works.
