Well if the R.A. stands for the Rajasthan Armoury, this is a company that says it has been making muzzle loading barrels for use in India since 1959. Your barrel was made January 10th, 1982. The stamp that reads India was added later when that barrel was placed on a gun for export.
I say IF the RA stands for that company as it is a standard letter stamp that is being used, so it would be easy to fake, but in your case I think it's legit..., my sergeant's carbine has the same markings.
The company says it began making muzzle loading arms for farmers to defend themselves from wild animals, and I'm guessing that the cost of a modern firearm was very high and/or as India had only been independent since 1947, perhaps modern rifles were prohibited.
Note that some folks claim that importers of Indian guns refuse to say where they are made, the barrels are not marked, and they are made only for display. Well if the barrel is made by this company it's clearly marked, and says when and where it was made, and it was made to shoot.
LD