I don't know about the sling, but do not even have a stock in the same vicinity of the gun unless you have the SBR paperwork, they will nail you to the wall. Vertical foregrips are also a no-no.
I hear that, not gonna happen here.
Once a paratrooper, always a paratrooper, just remember, feet and knees together and make sure you hit all five points of contact, especially the fourth...............