Andrew,

Manton and Co still exists as a business in Calcutta and if you know someone there, you might be able to get them to show them the records. It can be difficult dealing with them from overseas, though.

Whenever you have time, please do try and post pictures of your rifle here. As the official forum pesterer for gun and hunting pictures, I am fond of telling everyone who posts about a gun that they need to show her pictures off. Wouldn;t you brag if you had Keira Knightley on your arm?

Good hunting!