I'm an archaeologist working on a collection of dumped WWII materiel associated with a RAAF base in Darwin Harbour, Northern Territory. We've recovered a couple of machine guns that I'm almost certain are aircraft version Browning .303 MKII. My knowledge of machine guns is fairly limited though (!) and I'd love to be able to have ID confirmation from an expert. (And please forgive any massively ignorant questions from me!). I have managed to get serial numbers off both of them though - MK II / B 136.752 / B on one and MK II B 868.881 / B on other.
I'd also very much appreciate any thoughts or insight into these guns and whether there's any way to narrow down what type of aircraft they may have come from based on fittings and mounts. One has been largely stripped, is missing back plate and breech cover and has had the barrel / cooling jacket bent, so doesn't give much info except for the mounting lugs and brackets, I'd guess. The second has several fittings still attached, has a different cooling jacket arrangement and has spade grips (so I'm figuring it must be from a flexible mount?). I'm also unfamiliar with some of the fittings; it seems to have a feed chute of some type that I've never seen before.
Unfortunately, both have been in the water for around 60 years and aren't in great condition. They were also both heavily covered in marine growth and concretion and I've only been able to remove some areas of concretion without breaking things.
I've attached a few photos of both guns. I'd very much appreciate any thoughts, advice or suggestions for research.
Thank you very much.