I purchased a Disc Rifle the first year they came out and I always took apart the bolt assembly and cleaned it. There is absolutely no rust on this gun and it looks like new. It just takes a little more time, but it's well worth it.
The disc rifle is an excellant gun and it will give you years/lifetime of service if taken care of properly.
The best load for my disc rifle (5 shot, one and a half inch groups)was the 300gr. Barnes MZ, and (2) 50gr. Pyrodex Pellets. The group opened up a little using (3) Pellets, and I usually used this load for hunting, for the extra velocity/energy.
Good Luck with your new rifle!