No4 Mk1 Maltby Rear Sight Question

I have acquired a No 4 Mk1 (Maltby) as a restoration project. The original rear sight (Mk3 stamped) was damaged and I purchased a milled rear sight (B stamped) as a replacement. I found out that the B stamped milled sight will not fit on the Maltby. pinning it to the rifle is no issue, but when the sight is flipped down, the top edges of the sight are slightly larger that the recess and the rear sight will not fold down all the way.
I have seen pics of No4 Mk1 with milled sights, stamped sights, flip sights, but wondering why this milled sight will not work.
Milled sight was purchased by Numrich (Rear Sight, Milled, Blue Steel (800m; Micrometer Click Adjustment For Elevation)

I am looking to replace the milled with the stamped rear sight but any ideas why the milled would not work ?

Thanks in advance

I think it's a No5 sight. Mo4 goes to 1300m.

Yep, 800 yds is a #5 sight. Still, it should fit. I wonder if you'd show us a pic of the problem?

I'm curious to see it as well. My 1941 Maltby came with the 2 position flip sight which I quickly changed out for a nice condition Fazakerly No4 sight. It fit and works perfectly as should yours. Is it possible that your rifle was dropped onto the top of the receiver peening dents that are blocking the way? Or have you become a victim of Numrich's offshore reproductions sold as the genuine article scam.

Don't get me wrong some of the stuff is really good like the replacement bolt I have in this No4 and some of it is truly awful like the stacking swivel I bought from them for my P14. Had to grind like crazy to get it to fit in the band and the E marking is 3xs the size it should be, it's also painted semi flat black. The screw they sent with it was original however go figure. No notation or description that it was a reproduction at that time.

Thanks for the quick reply. makes sense. Appreciated.

I will send the pics later this evening

Pics of the sight as well as positioned on the rifle

It's possible that part has no military origin. Numrich has several outsources that are producing military type products. Why don't you return that questionable piece and PM me your address, I'll send you a used but original machined sight like you want... At no cost... It has all the parts needed to mount it.

As always Jim being a true gentleman.

I totally agree not a real part. Most likely of Asian origin and not to original specifications. Get your money back.

I got a Enfield sling swivel from Numrich recently. I was expecting an original but it is a repro as mentioned above with the giant “E” stamped on it. :/