they are accurate but dont exspect dime at 200 yards. you should be able to get sub MOA at 100 yards. as far as cleaning give it a good clean job to start with, and i cleaned mine after the next 50 rounds. but after that shoot untill the accuracy drops off, for alot of people that 250+ rounds.
the reason people get such great groups with these guns is because alot of people put 16+ power scope on them and use bench rests. i can cover 5 shots witha dime at 50 yards with a 12x scope and bipods. at 75 yards i can get about the same. i havnt shot targets past that but i have hit a gopher at 155 yards. mines a marlin but they have similar accuracy. www.rimfirecentral.com has lots of info on the 17hmr.