Yes use a brush and a good cleaner. Also remove the breech plug and clean the threads of the plug and inside the threaded part of the barrel. If the guy didnt clean it, you more than likely didnt get a good trade. Hopefully the barrel and threads arnt pitted to bad. I personally would take the entire rifle apart and inspect each part closely and clean everything and put it all back together. Also remember to lube the breech plug threads.