You only buy guns once, isn't too much need for a refund imo
It's not like they really get nerfed to a point where they're unusable or aren't worth the price, you guys seem to forget these cheaper guns HAVE to be worse than the things more expensive than them lol

Just checked wikipedia on the mp40..
"Fully automatic fire was the only setting, but the relatively low rate of fire allowed for single shots with controlled trigger pulls"
The game seems to reflect that well