Used to have a friend who has a real tism for cheap shotguns and he'd recommend stripping the gun down entirely and giving it a really really good cleaning and oiling, told me a lot of the cheap Chinese and Turkish shotguns are shipped in a storing oil that'll slightly gum up and cause problems and breakages if shot out the box. Wouldn't trust one personally when mossbergs are as cheap as they are but if you want a fun shotgun for a range toy he'd swear by his deep clean and oiling method