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 Restoring old dirty cartridges - example.

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smootik
Modelgun Perfectionist
Modelgun Perfectionist
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Number of posts : 1784
Location / Country : Poland
Registration date : 2009-03-03

PostSubject: Restoring old dirty cartridges - example.   Mon May 17, 2010 2:59 pm

Once upon a time I discovered that a mag that was supposed to be empty holds several fired cartridges.

I have no idea how long they have been left in such state.
In any case this is a good example why you SHOULD clean carts as soon as possible after firing :-)

Carts could not be unscrewed. I had nothing to lose, these were unexpected carts anyway.
All delicate attempts failed until I took two sets of strong pliers and using a lot of force "cracked" carts open.
As you can see from pictures, they have now a lot of scratches on the outer surface, made by jaws of pliers that had to grip so hard before carts could be opened.

Inside there was a lot of rust - these are Marushin style carts with steel firing pin in the base.





The first step after opening was removing as much rust as possible. Some of it could be scrapped off, but in the end all parts went into a cola bath. Cola contains orthophosphoric acid - it combines with rust, converting red iron oxide into black ferite phosphate. That black cover can be then remove, uncovering clean metal (or more rust to be removed).
Next pictures show cola bath preparation, a piece removed from cola bath with now black surface of the pin, and finally - pieces scrapped off - you can see colour difference between converted rust (black, on the right) and original (red).





Once rust was removed, cartridges were made more shiny using "vinegar bath" method mentioned in this forum. Prepare a small bowl, put all parts there and pour some vinegar. I use spirit vinegar, as white vinegar (wine) smells too much for my liking. Then pour some hot water, leaving place for the foaming effect that could spill over. Finally add baking soda (a large pinch or two) and watch the foaming water. After this is over, clean cartridges from vinegar under water, and then dry them out (to avoid rusting again !!!).





The last step would be to restore surface by filling scratches, but I have not discovered a satisfactory method yet. Steel wool or other polishing method will remove sharp edges, but scratch is still there.

You can see that pins in the base are not uniform, have different lengths and do not look too good. This is effect of material removed by rust. Remaining steel bits were left with black phosphate cover.



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