Originality of 1915 Enfield Mk. III

I recently purchased this 1915 Enfield Mk. III complete with magazine cutoff and volley sights and brass stock disc. WW1 rifles aren't my primary interest area, but this one stood out for it's overall condition and substantially original configuration, although as I have examined it in more detail I'm noticing a few things that have been altered. For instance, although it has the screw in the nosecap, it's missing the stacking swivel, and the windage adjustable rear sight has been replaced. The current rear sight has an older serial number lined out and is restamped with the rifle's serial number, which also matches on the barrel, bolt, receiver and forend. I also believe the barrel has been replaced if I'm correct that the '20 mark on the knox form is a barrel date. The barrel is also marked "HV" right behind the rear sight. There are some markings on the forend behind the nosecap that look like rebuild stamps. I'm curious if there is any significance to the R or EB markings.

It's been hard to find comparable sales of rifles in similar configuration to assess value. I think I did OK on it for a bit over $700. It was more than I really wanted to spend, but I haven't seen too many SMLE's like this so I figured why quibble over a hundred or so.

I welcome any additional thoughts or comments about it. Here are a few photos.

https://www.milsurps.com/images/impo...rkTdAmrh-1.jpg
https://www.milsurps.com/images/impo...9tIgWsNh-1.jpg
https://www.milsurps.com/images/impo...n3iEGMOh-1.jpg
https://www.milsurps.com/images/impo...DQSgFLfh-1.jpg
https://www.milsurps.com/images/impo...1xcnPpjh-1.jpg
https://www.milsurps.com/images/impo...GOtmGozh-1.jpg
https://www.milsurps.com/images/impo...VZTagiyh-1.jpg

Sum total of the parts will come to $700 I should think. How's the bore?

Others will know more, but I reckon that's a good rifle, at a good price. Windage adjustable rear sights often come up on ebay if you wanted one; but once zero'ed by adjusting the foresight blade I find I don't need to alter the rear sight, I just aim off if shooting at long range with wind.

If the sight on it wasn't serialed, I might consider a swap, as it does retain the asymmetrical sight protector, but not to a numbers-matching configuration. I was more interested in understanding what the markings might tell about the rework history of the rifle and any other updates I might have missed.

The bore is a little fuzzy, but overall pretty nice with strong rifling and no visible pitting. I will probably put a few rounds through her this weekend.

It is not uncommon to see a rear sight re-numbered when it has been replaced with a serviceable used part.
I had a similar crossed out marking and re-numbered rear sight on my No1 MkIII* rifle

Looks good to me. "EB" is likely someone's initials.