Your rifle, RIA S/N 418xxx, can correctly have any bolt made prior to 1928, to include straight-handled casehardened bolts. It can also correctly have an RIA straight-handled "NS" or "R 10" bolt. Or it can have an SA curved handle bolt marked "J 5" or "N S" (without periods) atop the handle.
E-mail for correct stock markings.
Hope this helps.
J.B.