Republic of Mexico (RM) marked Remington Rolling Block

[Anzac15]

Just got this one in, a Republic of Mexico contract Rolling Block. 'RM' is stamped on both receiver and barrel. .43 Spanish. Hand made butt and buttplate. Very little info I can find on Mexican RRBs, the majority I find online are in 7mm Mauser, and sport the Mexican crest on top of the receiver. I understand RM marked examples are pretty scarce.
RRBs continue to befuddle me as far as models and numbers go, and this one is no exception.
This rifle has led a rough service life. Would love to know it's history and how it got here.

[Anzac15]

Well, having trouble with pics. Try later.