Which rear sight for No5 clone?

[TCS-5]

The Parker Hale De Lux No4 sporter has now been converted to a No5 clone. Barrel is now 18.7" from breech to crown before the No5 flash hider and blade sight were installed

What it was...




What it is...




I was looking for a No5 rear micrometer sight but it was suggested on another board that I need a Mk1 micrometer sight because it really was a No4 rifle...

Hmm, as far as I can see, the mount for the rear sight on a No4 and No5 are the same. And the same distance from center of bore. So, if the No4 had a No5 length barrel, wouldn't the Mk1 sight graduations be totally off?... I figure a No5 graduated rear sight would be what's needed. Hmm, Make sense to me, but I ain't no armorer or gunsmith.

Please confirm or deny my assertions... With reasonable explanation.

Information

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[browningautorifle]

I believe the only actual difference between the #4 and #5 sight is the graduation. 800 for the #5 of course. Curtailed range because of a shorter barrel...you don't need a full 1200 or whatever the rifle was...

[TCS-5]

Yes, mechanically they are the same sight but I don't think the marks up to 800 yds on a No5 sight are in the same place a the Mk1 sight because of the lower velocity caused by the shorter barrel....

Will probably have to wait till tomorrow for our friends across the pond to be up, bright eyed and bushy tailed, to get a definitive answer...

[Maxwell Smart]

I'd use the 800 yard sight. The changed sight graduations reflect the shorter barrel (which affects sight radius and bullet ballistics).

Most, if not all, of the of the 800 yard sights which I've seen also have a different elevation screw, which gives finer adjustment.

The 800 yard sight will also crank a lot lower below 200 yard setting than a 1300 yard one will.

[TCS-5]

Thanks Max... This is confirming what I've been thinking.

That's good to know about the finer pitch on the No5 adjusting screw.

Sorry, I forgot that our friends down under are just getting up...

[Maxwell Smart]

Picture of the two types of sight. See how the elevation screw on the 800 yard one is different.

This means that the leaf on that sight only moves about half as far per click as a 1300 yard one does. (.00425 vs .008 ")

Doing the calculations, I believe it can be shown that for practical purposes

No 5 rifle, 800 yard sight 1 click moves POI by 2/3 inch @100 yds.
No 4 rifle, 1300 yard sight 1 click moves POI by 1 inch @ 100 yds
No 4 rifle, 800 yard sight 1 click moves POI by 1/2 inch @ 100 yds

[Peter Laidler]

Max is right in thread 4. The scale differs to reflect the shorter sight radius and slightly different m/v between the two barrel lengths.

The actual adjusting screw and nut thread system is pretty academic (or a waste of time) because it doesn't matter HOW you get from stop to 2 or from 2 to, say, 6 on the scale. As long as the screw and nut match. You'll find that any needy rifles that came through our huge workshops will have either the No4 or 5 screw/nut.

As for what sight to use, then the scientific answer would be to set the rifle up in an EWnfield rest and select the best sight to suit the rifle characteristics. But as you'll probably be using non military commercial ammo, it'll be at best, a good compromise either way. Just my thoughts

[TCS-5]

Thank you Peter for confirming what would be the best sight.

As for ammo, lets assume MkVII service issue. I try to set up all my milsurp rifles on the service cartridge they were designed to shoot. As posted before I have some RG MkVII '49. Also, the Greek HXP from what I can discern was made to replace MkVII and was given the L!A1 nomenclature in... what 1983?... There's more on the market of late at reasonable prices.

[browningautorifle]

Max is right in thread 4.

Or...Jim was right in the first place...

[Peter Laidler]

You're right, HXP was made to replicate Mk7. And it did too! It was also given an L- type ADAC number but it wasn't on the ammo, just the paperwork.

I wonder why someone can't ask HXP to make another million rounds. 1 million rounds of ammo will fit into the back of a Bedford lorry - so it's not a lot. Or why can't India make several million Mk7 for export I often ask