Brass build up on Lyman M expander die

Bayou

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Feb 21, 2010
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I saw some peculiar looking scratching on the inside of some Lapua 308 necks recently and traced the problem to brass build up on my Lyman 30-Long M expander die. The stuff is really stubborn and I'm having a tough time removing it. So far I've worked on it pretty hard with steel wool which has gotten most of it off. Then I tried some Shooters Choice copper remover but that seemed like it did nothing. So just wonderinng if any others have experienced this and how they removed the brass residue?
 

Fuzzball

Gunny Sergeant
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Jan 19, 2009
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Re: Brass build up on Lyman M expander die

The M expander system is probably THE best expander on the market for both cast and jacketed bullets. Rubbing any dissimilar metals together under high pressure and without lube invites 'galling', in which tiny bits of the softer adhere to the harder as firmly as it welded and it get worse with each pass. Galled brass is what's getting on your M expander.

If you have a drill chuck large enough to hold the upper end of the stem you can hold 4/0 steel wool against the expander plug and easily remove the galled brass in a minute or so, and without damage to the expander. Or, you can soak the plug in any bore cleaner/brass solvent of your choice until it's gone. And then put a tad of lube in your case mouths to prevent a recurrence.
 

Bayou

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Feb 21, 2010
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Re: Brass build up on Lyman M expander die

Thanks for the suggestion. I'm hesitant to let stainless steel soak for long periods with copper or brass removing chemicals so I tried the drill and steel wool method first and that worked. I recently switched to graphite dry lube for neck sizing operations as the clean up is easier. I just blast the case with compressed air as opposed to running them through the tumbler (aqueous detergent solution w/ SS media) to remove hydrocarbon oil based lubes. Maybe the dry lubing isn't working for me, I'll have to think about returning to the wet lubes.