If your talking about a 742, basic cleanning is all you should attempt if your not famillure with the workings of the gun. If it is in nasty shape, I would recomend takeing it to your local gunsmith to tear down, clean and inspect. If you want to learn how to do it, I would recomend getting a teadown and re-assembly manual befor you attempt it, there is too many steps involved to type it all down and make it for you to understand!.