Mk. 1's should be dated 1873 or 1874. Without pics it is almost impossible to give a value but it definitely is more than $350.00 in my opinion..."if" it's a Mk.1! Mk. 1's which are complete, genuine, in excellent condition and untampered with usually go for $2,000.00 plus on some of the internet antique rifle sites. Certainly warrants more investigation. Much less $$$ if it's one of the Nepal cache rifles.