Certainly
https://en.wikipedia.org/wiki/Mughal_Empire
Look at the later parts of the history section.
Nice. It looks like the fellows in charge just fell apart, just in time for the British to step in and take over.
Oddly enough, the British did produce guns in India. And had the infrastructure set up for Gunpowder, etc. for example
https://en.wikipedia.org/wiki/Ishapore_Rifle_Factory.
Any ideas about the amount of gunpowder being produced locally? In other words, were they exporting it from India, and if so in what quantities? They mentioned 'Gun and carriage' works set up in early 1800's, this means artillery guns? Was ammunition (either infantry or artillery type) also being manufactured locally? I mean, I would just assume that it was, but I suppose that an argument could be made for that not to be the case. Either way, interesting info there. I would really like to know if the local arms industry made 1850's onward India a net importer or exporter, and whether these facilities could be captured and held, or just destroyed (perhaps many times), as needed.
So they weren't at the end of a long logistical trail. They had Indian troops, and local military infrastructure - and short of their own sepoys/troops rising up, have control of their own local logistical base.
Correct me if I am mistaken, but wasn't the majority of their troop strength native troops? In other words, rebels couldn't hope to get British troops to turn coat, but perhaps they can get fellow Indians to do so.
And a sea that they control. They have both the long-distance secure backup for their supplies, but also local resources to fight the war from.
Also, with Britain in control of the seas, how are the Indians getting access to arms? through Afghanistan? Britain would be able to embargo any trade to India that wasn't with them. It would not be a small feat to smuggle the amount of arms needed to fight that war.
Your major mistake here is that Vietnam was able to import modern weaponry, and had incredibly good defensive terrain. India, has all sorts of terrain, vastly exposed to naval landings, and outside of British control, has no access to import modern weaponry. If there isn't a great victory on the side of the rebels early on, you aren't going to have the sheer number of bodies needed to bury the troops in British Employ (unless those troops defect too).
Overland works for arms smuggling, but you gave me an evil idea just a bit ago, what with the local gunpowder works. BTW, were small arms not made locally till OTL 1904? I mean, not having to import vast amounts of heavy loads of gunpowder is a boon (until such facilities go BOOM), but if rifles and ammo is still having to be imported, then they still have a long way to go.
For this type of warfare, infiltration, bribery, blackmail, and assassinations would play a large part alongside raids of powder magazines and arsenals, as well as just plain infrastructure and British property destruction.
Basically, I would expect the first phase would target all facilities that were deemed 'doable' and 'must kill' type of things, and this would at the least have to include top British officials, local stores of arms and ammunition, lots of British property, and as much else as could be managed, with whatever limited forces you would start off with.
You know, it really wasn't my intention to get all into Indian history and all, but I wonder if there is a computer game on the market that could be utilized to simulate such a war as we are discussing here? With my very limited knowledge about Indian history, it might make such a game very interesting from the point of view of a player playing the Czar, sending agents into a strange land and studying how to best kick the British out, or baring that, just make India into a loosing proposition, rather than the most profitable portion of their empire.