Try Gunpartscorp.com also known as Numerich
That is the T-900 system, restricted by Marlin. sales@countrygunsmith.net
It means its 925 sterling and the M is for Mexico City.
925 m/c
Marlin proofmark the mark first used was the letter M in a circle. In later years (after the model 1889) the mark used was the letters JM (John Marlin) in a oval
925 shows that it is made from Sterling Silver and M M D is the Scottish maker's mark.
If it's Mark 925 why does it look gold
· Mackerel · Marlin · Minnows
Entire books have been written on the Marlin company.
· Mackerel · Marlin · Minnows
The letter M prefix to your serial number indicates that your Marlin rifle was made in the year 1955.
If your Marlin model 57 levermatic is showing between 80%-95% of it,s original finish,it would be worth between 200-300 dollars.
925 is the silver content,equaling 925 parts silver in every 1000 parts of total mass used.The m probably stands for milor an italian silver jewellery producer of high quality workmanship.good luck with this and i hope it helped.phil