Help IDing some British and European firearms

[RDGAC]

And now a bit of a puzzler, at least to me. What looks like an ordinary enough flintlock musket, but seems a bit weird to my ignorant eyes.

Firstly, although it bears a very clear maker's mark and date (which is nice, though I know nothing about Corson (and?) Carr), the crown stamp, though positioned where you'd expect it to be, doesn't have any lettering to accompany it. The crown itself also looks a little roughly done, even for the 1750s.

Second, its proportions are odd. I've done a little digging and it seems most likely to be a 1756 Short Land Pattern, but the barrel's too short (39.75in), and more importantly, the bore's too small - .62-.65 (measuring roughly with a ruler), rather than the .79 or so I'd have expected. Even if the barrel has been, at some stage, cut down, it is still under-bored.

Thirdly, the proof marks. They're incredibly small (useful, that ), but I think I can make out a single "Viewed" mark - and two Black Powder proof marks. Of course, I may be wrong, and hopefully the photo provided is useful, but my first thought was that the barrel has been reproofed at some point in its life. However, if that is the case, one wonders what precisely led to its needing reproofing.

Anyway, herewith some piccies. Sorry if I'm asking stupid questions; I fully admit, and abhor, my ignorance. But I think a great man once said that, "To ask may be a moment's shame; not to ask, and to remain ignorant, is a lifetime's shame".

While waiting for these to upload, meanwhile, I took a look at the lock. The workmanship's a world away from that of my old jezail, and the lock is in very good condition - except that the sear's missing! And it's covered in a strange, greenish-yellow, sticky goo, which I assume was once oil or tallow of some kind...