Welcome to the forum Pastor. Yep the barrel will get hot under rapid fire. Don't know how quick someone could ruin a barrel. One member fired a 90 rd drum mag untill his barrel changed colors.
I don't let mine get hot, unless my life depended on it. I've riped a 20 rnd mag a couple of times, it does get hot. Not much to do about that except slow it down.
As far as accuracy there are a few nickel, and dime things you can do to at least double your accuracy say at a 100 yds, or any other range for that matter. Use a sand bag, and good shooting technique, and keep the barrel from getting too hot to test for accuracy. I use avg 5 shot groups to record before, and after so I know wheather accuracy is improving.
1. Select ammo your mini likes. (I'm not talking expensive match ammo either). Some will shoot twice as tight a group as others each mini is different.
2. Hang a $19.95 muzzle brake in the end of your barrel, it will cut your groupage in half. It is a user drop in part.
3. Bed your stock. It will tighten Your groups, and get rid of the flyers.
4. Trigger job. I haven't seen many people shoot accurately with a 7 to 9# trigger.
If you do these things, and use good marksmanship you should be able to shoot groups 1 1/2" to 2" with select factory ammo and a scope. Expect a little larger with the peep sights.
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