Seems like the disk of hot gas escaping through the cylinder gap would be just as bad though. I suppose they could have a gas seal mechanism like the Nagant M1895… in which case they’d be continuing the bullpup tradition of added complexity.

Paintball - he’s not very good at it

I dunno, I could kinda see it - they don’t understand a ton of their own tech, and have folded religious belief into even basic maintenance routines until they can’t tell whether lighting incense or chanting as they work changes the outcome. I don’t know about the admech, but the imperial guard types seem to believe every device from a heavy bolter to an ancient and venerable space marine tank are all equally likely to have machine spirits animating them - presumably they got that thinking from their tech experts. There’s also the sort of outlined belief that tech is sort of… naturally occurring? and that it’s heretical to invent new stuff when the correct process is to discover it somewhere.

Add to that the fact that the quality of their tech has declined pretty drastically from their past (aren’t most STCs, which they basically worship as the best of their modern tech, like the crude, sturdy equipment you’d give a colony that was just starting out?) and the fact that some of it is sometimes possessed by literal daemons or other ancient abominations… it sort of seems like they’re in over their heads compared to the others.