Rick, this topic has indeed become totally fascinating with this thread, and thanks to you and the guys who have brought your experience, examples and expertise into these pages. For me it has been an entire learning curve, and actually it was my goal to learn more on these after I finally found one!
I hoped that this discussion would not only become a kind of resource for material and observations on these guns, but increase awareness of them in the collectors field, and that has definitely been achieved thanks to you guys.
It does seem like the character of these jezails indeed represents that of 'frontier weapons', that is arms which are often, if not typically, assembled with composite components and locally made elements bringing them together.
With the formidable reputation of the jezail itself as a deadly weapon with the skills of both the artisans crafting them and the tribesmen using them, it would seem the British locks became the standard for that particular element.
While the locks themselves seem to have been in abundant supply, the tribal armourers of course learned to duplicate the markings of British EIC locks in degree. Naturally these were more crudely applied and unawareness of the proper associations of the markings' purpose led to incongruent combinations such as VR (Queen Victoria) with 1815 date or similar pairings.
It seems like even when markings were worn off, there were even attempts to 'touch them up'. It is as if the markings themselves carried some sort of imbuement to the power or quality of the weapon.
As you have noted, the possibility of export of these locks into these regions by vendors dealing with the EIC for specific trade with tribal groups is a distinct possibility. There were many instances of such 'private enterprise' with arms in India before and during the 'Raj', and while most weapons filtered through government channels for forces there, there are many cases where items were sent there outside these administrative venues.
I agree with Kubur, this example you have posted with the wonderfully marked lock, the maker who seems well represented in these, and especially that fantastic barrel!! This example perfectly illustrates the kind of comprehensive quality of these guns quintessentially !!
Stu, thank you for that link.....I had no idea of Cornwallis involved with EIC. Naturally we know him well in the US from our Revolutionary War history but totally unaware of his extended career into EIC.