Bigwagon:
Some photos of details No. 4 Mk. I (T) 0C820, which was one of the 1,403 No. 4 Mk. I rifles converted to sniper equipment at R.S.A.F. Enfield are on this page on my web site. https://captainstevens.com/military/...ment-markings/ Yes, it also has the U.S. PROPERTY mark as discussed above.
Some things for you to check on:
1. Is there "S51" stamped on the underside of the butt, aft of the pistol grip?
2. Is there an inspection mark on top of the front scope pad as shown on 0C820 on the web page above?
3. When the butt is removed, is there a rifle serial number stamped on the top ledge (hidden when the butt is installed). IF a number is present they usually left off any letters, so it might read "1064".
4. Is there a scope serial number stamped on the top of the wrist of the butt, below the cocking piece?
5. Is there a "T" on the left side of the body flat? The partial detail views in your photos suggest there is no "T", but it would be good to have confirmation.
I am in the middle of selling (just awaiting final payment) another No. 4 Mk. I (T) Stevens-Savage rifle, serial number 0C5130 which also has the F.T.R. stamp superimposed on the U.S. flaming bomb and also has the "TR". It does not have the "T" nor the Enfield examiner's mark on the topside of the front scope pad. It does have the matching No. 32 Mk. III scope 23815 fitted to it during F.T.R. The butt is an "S" Stevens-Savage marked one, with no "S51" The rifle was fitted with a MK. II cocking piece and a Mk. II rear sling swivel and a sniper's swivel in front of the magazine. It has an Enfield marked low-wood fore-end. It retained the "S" Stevens-Savage backsight, modified of course to clear the scope. The scope SN is stamped into the wrist of the butt. The magazine is engraved (not stamped) on the bottom "0C5130" It has the U.S. PROPERTY mark as discussed above. The bracket is also numbered to this rifle. Bigwagon - if you want to send me your email by private message, I can send you detailed photos of both the factory original 0C820 and the F.T.R.'d 0C5130.