Hey Hey, just thought I'd add my 2 cents..
I spent 18 years in the US Army, and .. I have a mini! ..
I did a video shooting the mini at 100 yards.. I'll link it again.. and here's a pic of my working on Memorial day. As others have said, the pull is a bit long (with the standard stock, the ATI is adjustable), and recoil
*slightly* more than the AR, but I can keep up with most of them .. =)
I do have to disagree with Gundoc on one point, perhaps I was lucky, OR the stocks had improved on the 581's, the stock fit on mine is anything but sloppy.. again, maybe I just got a lucky stock . =)
I am guilty of being a mag grabber when not firing off the bench, and yes, with NON Ruger magazines it will cause feed issues.
Oh, on that note, Mag swaps are a tad slower if you are concerned with that, I typically use my new mag to detach the empty magazine.. there's a video on Rugers site demonstrating that. Basically you use the new mag to engage the mag release and push off the spent magazine then insert the new magazine. A bit akward until you get used to it..