One thing the Mini-14 is known for and I can attest is that they are typically very over gassed and will chuck brass into the next century. Beware of this if you're on an open firing line because you're range neighbors may not like getting a constant brass shampoo. If you're mini is over gassed and it's an issue for you a tunable gas block is a sure fix or and even cheaper, simpler fix is an aftermarket gas bushing replacement which is a two minute install.