I have just revitalised a 39A a while back and I just cleaned out the crud, sandblasted all the metal and guncoted (cerracoted) it all, installed a silencer and scope Then sanded down the wood and used many coats of Tung oil on all the wood parts - it is easily the most shot of all my rifles now
With the silencer... it is so quiet that even my wife doesnt know I'm shooting around the yard! Pity they dont make silencers for wives... hahahaha!!
If it cant be fixed by a hammer or a bullet , then its REALLY broken !
Team 30-30 # 403
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Team Rimfire # 143
Team Marlin Express.
Lot of time it's easier to just let it soak in something for a while such as kerosene say 4 hours, your favorite tranny fluid overnight. That softens stuff up and soaks in with lube that does have a cleansing effect.
Next something strong like paint thinner to take the goo from the tranny fluid and make the heavier crud to be removed. It's at this point I revert to the goggles and air blaster for the high filth areas with the build up. Dental picks which you can get industrial versions in many shapes, for impossible cling ons. Use a good magnifying head gear and a fixed clamp you can really remove even the nastiest stuck on foreign objects.
Regular maint makes all this much easier on the blood pressure but then when you find a deal on a project you come here and share it's resurrection WITH PICS OF COURSE, good luck on your project.
God Bless Our Troops -- Retired Tool & Die Maker -- The center of an Aspirin is the same size as the center of the moon, aim for the center.