combat, the JG G36C comes with a barrel cleaner. Just put a small piece of paper towel on the end and push the into the the barrel. As for checking it out, why don't you see how it is first.
Perhaps you don't need help at all.
Oh yes a minor update to the review I guess. The JG G36C has been fielded a handful of times and it's performed very well. Shoots as straight as a TM/CA and absolutely no problems from the gun or battery whatsoever.
A few thousand rounds have been shot through it and it's still fires like new.