I just acquired a Enfield 45-70 Sporter with a 21-1/2" octagon barrel. There's no markings on the barrel. The action is a 1944 MK4. The checkered stock looks like a Gibbs Summit. I've searched but can't find any info about it
Back in the 70's there was a craze on to convert the Siamese Mauser or the British Enfield to 45-70. I don't remember who the main company was. If you have access to gun magazines or Gun Digests for that period you will find info there.
Here are some pics of the Enfield
The main company was Navy Arms using the name Gibbs Rifle Co. Used to be in Ridgefield Park NJ, are now located in Martinsburg WV. I found some of their conversions that had round barrels with Navy Arms stamped on them. My barrel has no markings
Check out Gibbs Rifle Company and you'll get some hits. Gibbs also did 308 "Jungle carbine" conversions too, were a few on the auction side of the house here. I have their lesser 45/70 conversion, uses the military stock and forend with some modifications. Had it drilled and tapped, put an old Weaver on it.
Gibbs also did a pretty good US 1903 sniper version.
FWIW, I'd scrap that rear sight and put on an Enfield adjustable peep.
Looks like a Set of SILE Enfield stocks, popular back in the day . Looks to me someone cut off the rear ears where the peep sight goes.
Neat rifles, Big game in your area??