Mitch, back in about 1994 I suppose, I bought into a law enforcement deal direct from Ruger - their stainless mini-14 with flash suppressor. Now it was substantially less than what you had to pay but, at today's prices, I think you did very well. Up until about 89 or 90 or so, my agency's standard issue long gun was the mini-14, but then we went to the M-16 and, today, the M-4.
You can;t really ask an older model mini to shoot alongside the M16 or AR....it just isn;t a fair matchup. The mini-14 carries the "accuracy cloud" over its head because it just is not a match rifle. But the accuracy woes I've heard through the years seem to me to be exaggerated, and sometimes greatly so. I mean, guys will say "I had one of them mini-14's and couldn;t even hit the target. I just got fed up one day and threw it in the weeds alongside the culvert." When I hear stuff similar to that, not only does the guy's credibility fall to about zero, but I'm thinking maybe he should be shooting a shotgun or maybe watching TV or something. My little wood-stocked mini-14 (still in absolutely
pristine condition), will shoot 3" and under all day when I'm doing well. That's fine enough to do what a "rancher" needs or wants done, and that's who it was marketed for. If you shoot and learn the rifle enough, and use the same ammo, the coyote or racoon bothering the chickens isn;t going to bother them anymore if they're within 100 yards or so.
Now, I have a little mini-30 stainless that shoots much better at 100 yards, but that's an aside from your question.
I think you did good. There's nothing like breaking down and cleaning a Ruger mini, and even if you don;t, it'll still cycle and shoot just fine.
ON EDIT: About the rapid fire and barrel warping - I cant say about that, but I can say no rifle benefits from shooting so much ammo in so short a time as to heat the barrel to extreme temperatures. Even the M4 we shoot full auto just for familiarization (and fun), but the most accurate way to fire any full auto weapon is in short bursts (we use 3-round bursts). I've had my M4 for about 10 or 11 years now, and it's never had more than 20 rounds fired through it on full auto. It still shoots acceptably accurate at 100 yards with the switch on semi-auto, but I wouldn;t take it to a long-range rifle match. First, that's not the M4's gig and second, I don;t think it's much more accurate than my mini-14.... I mean, not much. Now, you can shoot a mini pretty dang fast by pinning the rifle between your hip and elbow and "rolling" your index finger inside the trigger guard. After a couple of three or so magazines of that, it'll be out of your system and you won;t have to do that anymore. (((

)))