no.5 micro sight on a no.4?

[ssj]

Im no expert, just maybe 4 months ahead of you. You are seeing the same issues Ive had so much is fresh in my mind. Someone like Peter L. is the true expert.

and yes Im also finding Enfields fasinating, I'll admit Im hooked.

[Peter Laidler]

Hey......, hold on SSJ! I'm no expert by any means. It's just that I know a bit more than the average Joe about them that's all. And even then, I only know about the technical, engineering and manufacturing side. Not the historical stuff

[bow]

If i had correcly understood what you mean. ssj, you want to use a no.5 micrometer sight on a No.4 rifle? i just do it withouth any problem. But elevation doesn't match the range written in sight, because no.5 rifle has a shorter barrel and bullet exits the muzzle more slowly. So you could use it on a No.4 but expect a process of trial and errors.

---------- Post added at 04:30 PM ---------- Previous post was at 04:29 PM ----------

And ...yes, Sir.Peter knows about enfield more than any other.

[Beerhunter]

elevation doesn't match the range written in sight, because no.5 rifle has a shorter barrel and bullet exits the muzzle more slowly.

As I I pointed out earlier, it is mostly because the No.5 has a shorter sight radius compared to the No.4.

[S-A-M3]

I read somewhere[so don`t take it as gospel]that the No4 Mk1 sight, each click was 1/2 in at 100yrds. While the No5 mk1 sight ,each click was 1/3 in at 100. The writer was suggesting that the No5 sight gave a more accurate adjustment for service rifle shooting. I have never tried this and have no idea what it would do to the scale at longer distances!

[Peter Laidler]

As I understand it, the CLOSEST that you will get the click adjustment on a Mk1 sight is 1 MoA or approximately 1click = 1" at 100 yards. BUT, I must say that this is only a good ready reckoner type of theory.

To test it yourself and to see how close (?) this ready reckoner guide is, count the clicks from 2 to 10 on the No32 Mk2 or 3 sight - and it'll be 54. Now count the clicks on a No4 Mk1 backsight from 2 to 10 and it'll be approx 56 or 57 from memory........... Same bullet, same rifle..... There it is approx 1 minute of angle.

Not a lot of people know that....... But they do now!

[Maxwell Smart]

+1 for the "1 minute" clicks, Peter

My thoughts are that the adjustment "capability" for the 800 yard and 1300 yard sights depends upon how much the sight leaf is actually moved per click, and the sight radius of the particular rifle it is fitted to.

Given that the thread pitch of the adjusting screw on both sights is different, the leaf moves a different amount for each click (.008" for the 1300 yd sight, .00425" for the 800 yd sight)

The No 4 rifle with a sight radius of 28.74", has therefore "1 minute" clicks with its standard 1300 yd sight.
The No 5 rifle with a sight radius of 23.15", has "2/3" minute clicks with the 800 yd sight.

The No 4 rifle, fitted with the 800 yard sight, has not quite "1/2 minute" clicks.

These figures are got by using the following formula, using 3600 inches (100 yards) as the range.

[Range (inches) X change in sight elevation (inches)] / sight radius (inches) = variation on target (inches)

So, in theory at least, I believe that it can be shown that fitting a No 5 sight to a No4 rifle will give finer sight adjustments. The down side is that the actual marked range graduations are no longer much use, but then again they aren't much use on a 1300 yd sight either unless your ammo matches Mk7 ball ballistics.

[chainsaw]

I didnt go to math school,so I wont do the math but,could a person that handloads correct the differences in sights by changing bullet weight and velocity?

[Peter Laidler]

I could be wrong Max, but I have seen and fixed about a zillion No4's and 5's - but surely, the actual SCREW, adjustment on the Mk1 No4 sight and the Mk1 No5 sight are the same - as is the round matching cursor slide nut. From memory, I seem to recall that there WERE different types of No5 screws but only in that the thread was only partially rolled down the shaft........

[Maxwell Smart]

I could be wrong Max, but I have seen and fixed about a zillion No4's and 5's - but surely, the actual SCREW, adjustment on the Mk1 No4 sight and the Mk1 No5 sight are the same - as is the round matching cursor slide nut. From memory, I seem to recall that there WERE different types of No5 screws but only in that the thread was only partially rolled down the shaft........

It's been nearly 30 years since I've owned a genuine No 5 rifle, all I can say is that the measurements which I've quoted are from sights I have on hand now; whether these were ever part of the UK MOD system I do not know...

The 800 yards sight which I measured was one which I got off e-bay from the UK. It is in as-new condition, marked with a "P" and part no CR 318. The adjustment screw on this sight has a diameter of .140", and the thread is not rolled the full length of the screw. The 1300 yard sight has a screw diameter of .110"; it is not easy to measure on the assembled sight, but the 800 yard one is noticeably thicker. The leaf on my 800 yard sight moves half the amount of the 1300 yard leaf for the same number of clicks...

It could well be that this shiny new sight is a modern repro, so I went and dug out an 800 yard sight I bought 25 years ago, fitted on a No 4 Mk1/2. This one is marked with a "B" and broad arrow arrow stamp, with no "CR" number. The older sight has the same adjustments as the new one, so I'm still convinced that the 800 yard sight will give finer adjustments.