I'm not going to go into the reasons I wanted to use one like I did, just the technical aspects of a fire position.
I wanted a mobile fire position that had a certain kind of stealth. I used a long bed Chevy 1 ton van I had for my business. The idea here was to open the back doors just a couple of inches with the van parked and positioned so I had the correct field of view to the "target". It was my thinking at the time that I could have the barrel inside a few inches and it would muffle the blast report to a dull thud, good theory but I wouldn't advise it. It was something I did only one time (one shot), after that the barrel sticks out a few inches so as to hugely reduce the inside pressure inside the van. I got the impression that any dents would have popped out from the inside.
Let's just say that idea was flawed, a .50 develops a lot of pressure in a closed space and leave it at that.