I used to own that RNWMP carbine many years ago. It's a nice one, but I've advised the seller for the estate that it is likely not RNWMP. There is some variation, but for the most part, the Ross and Enfield Rifles/carbines owned by the RNWMP were stamped with an oval stamp, not a crescent shape. This one has a crescent shaped mark, which is not described in Phillips' book and was as far as I recall only used on the Winchesters, which were of course NWMP. The "Royal" designation was added after their time. There is no stippling around the edges of the stamp. The carbine has had its stock lightly sanded and a coat of varnish put on, and that was another issue with the stamp. The Canadian
Forces' M&D stamp and the rack number are rather faint, but the RNWMP stamp is deeper and newer. Since the stamps, if correct, would have been applied around the same time, they should all be equally faint. There is a faint other mark visible. IMO, the carbine may well have been in the Mounted Police service, based on the number stamped on the butt, but it has been massaged; I believe the RNWMP stamp is a fake. Others may disagree, but there are a lot of MP fakes out there. It is a sweet little carbine, mismatch bolt but otherwise complete and in nice shape. I have three, so didn't want it back even with a lower price, but if I didn't have one, I would buy it as a carbine, not as an RNWMP item. I believe the seller is going to lower the price.
Re: the sniper. I have decided to take the plunge and purchase the trials sniper. Even with several replaced parts, it is still a 1931 #4. Once I own it and have it in hand, I will disassemble it, take lots of photos of everything, including the mystery scope, and post them here for everyone to admire or castigate at will.
Cheers
Ed