no.5 micro sight on a no.4?

[Peter Laidler]

Can't dispute what you've got in front of you Max except to say 'well, I'll be jiggered.........' At least I was partially right in that some No5 screws are only rolled half way down and on the No4, each click is approx 1MoA.

I'll look in the tech library and see what the score is

Added later...
Querie solved. Who has the up to date No5 rifle parts list including amendment No4? Can't see the date but the front cover will be annoted WO-3111. Amendment No4 will be shortly after Amendment No3 dated May 1953. New page 7 (plus loads of other new pages that include the Grenade projector (an extremely rare item if eve there was!), the genade sight that was the same as the No4 and the shoulder pad and the now obsolescent short-thread screw and nut discussed above This amendment also shows the two screw bayonet grips and the now obsolescent Mk2 backsight with the usual WSE annotation.

My 40-BWS No5 has the No4 fully threaded screw/nut backsight

[Maxwell Smart]

One thing's for sure, when discussing Lee Enfields, a seemingly simple question can often come up with some interesting findings.

I will see if I can go back and edit my previous posts, to clarify that my data may not apply to all 800 yard sights.

The sight I got on e-bay will have a lot of friends around the world, the vendor was offering them in job-lots of up to 5 or 12; with the occasional whole box on offer. If it is one of an obsolete pattern, and had been sitting unissued in store somewhere, that would help explain why it looks so shiny and new.

[Parashooter]

At least on these two examples (original sights), there appears to be a difference in screw diameter and pitch. Given the slightly coarser thread on the 800-yard sight, the "click value" would be some 10% greater than the 1300-yard sight if both were mounted on rifles with the same sight radius - except for the fact that the 1300-yard elevation screw is double-threaded, giving it an effective pitch approximately double that of the single-thread 800-yard screw.

On measuring the two sights shown, each click of the No.4's sight moves the slide .008" - vs. .0043" on the No.5's sight. Consequently, the 1300-yard sight gives very close to 1.0 MOA per click with the No.4 rifle's 28" sight radius while the 800-yard sight has a click value of ~0.66 MOA with the No.5's 23" sight radius and would yield ~0.55 MOA on a No.4 rifle. (Pretty much what Maxwell Smart reports in post #17 on this thread.)

[Peter Laidler]

Ah, but the early '10 thread' sight assembly is not OBSOLETE, just obsolescent, so in theory, like Mk1 & 2 Bren barrels, you could find them coming through Ordnance stockpiles for absolutely years afterwards. It simple means that the factories have stopped producing the screws and nuts and thereafter, when stocks exhausted (hence the WSE annotation) you simply use the more readily available No4 parts.

Interesting thread which shows that while I knew that there were two TYPES of screw, hadn't digested the Technical spec in the EMER to understand that they were slightly different threads.. I wonder why they were different? It made absolutely no difference to the sight....... The crunchie still would it up so that it read 4 whatever the thread! Maybe that's why they standardised them