There are times when you will encounter a MILSURP with old caked-on, dried grease or cosmolene which defies removal by agents such as mineral spirits or WD40. In these cases the preservative coating has almost turned into a laquer or a carmelized/baked on coating over a long period of time. In some cases there will also be fine caked on dirt, and even some rusting, beneath the preservative. For these you can try soaking in laquer thinner or acetone with all the usual safety precautions. Rubbing with methyl hydrate can also produce good results and is worth a try. If these don't work, then you need to go to an abrasive, rather than a chemical/solvent cleaning. I recently worked over two NOS Springfield barrels, still in original factory cosmo and preservative wrap, which required some degree of abrasive treatment to get the metal clean before installing them
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What has worked in these situations is a combination of fine steel wool, dental picks for the interior edges and joints(make your next dental visit more enjoyable by scrounging some used picks from the hygenist), a double edged razor blade (remember these), fine wire (toothbrush style) hand brushes and a selection of wire brushes in a Dremel tool. A bronze bore brush works well to remove crud from pin/screw holes. The caution is not to scratch or damage the underlying metal finish by excessive abrasion. If going the wire brush route rinse the part well in solvent first to dry up the crud as much as possible. It is also best to have the part well dried before using steel wool or a razor blade. If you do this carefully you can get the crap off and avoid having to refinish the metal afterwards.
Gasoline is an old shade tree mechanic's approach which will remove grease and crud, but most folks have stopped using it because of the safety implications. Vinegar has been mentioned, but this will attack both parkerizing and blueing if left too long, so I would avoid it.
For a touch -up of parkerizing or blueing, especially edge wear, Brownells Oxpho-blue Cream is tough to beat.
.What has worked in these situations is a combination of fine steel wool, dental picks for the interior edges and joints(make your next dental visit more enjoyable by scrounging some used picks from the hygenist), a double edged razor blade (remember these), fine wire (toothbrush style) hand brushes and a selection of wire brushes in a Dremel tool. A bronze bore brush works well to remove crud from pin/screw holes. The caution is not to scratch or damage the underlying metal finish by excessive abrasion. If going the wire brush route rinse the part well in solvent first to dry up the crud as much as possible. It is also best to have the part well dried before using steel wool or a razor blade. If you do this carefully you can get the crap off and avoid having to refinish the metal afterwards.
Gasoline is an old shade tree mechanic's approach which will remove grease and crud, but most folks have stopped using it because of the safety implications. Vinegar has been mentioned, but this will attack both parkerizing and blueing if left too long, so I would avoid it.
For a touch -up of parkerizing or blueing, especially edge wear, Brownells Oxpho-blue Cream is tough to beat.
