You take it to a gunsmith.
Ross rifle was created in 1903.
very rare Canadians with no US mark ! 2500$
Ross Flood was born in 1910.
Henryk Ross was born in 1910.
Fred Ross was born in 1910.
Leo Cardwell Ross was born in 1910.
John Ross Taylor was born in 1910.
Agustín Ross Balcony was created in 1910.
Canada
In the age of the Internet a simple search with terms like "Ross Rifle" or "Ross Rifle parts" will turn up various dealers. Including your address, if you are into bricks and mortar stores to shop at will find local dealers.
Murray G. Ross was born on 1910-04-12.
Donald K. Ross was born on 1910-12-08.