Need help adjusting front and rear sights for zero on No4 MK1/2

[logandiana]

I have meant no disrespect to anyone. If it's come across that way then I appologize. I have come here for the wealth of information that some of these old timers have, but it seems like these old timers that I am speaking of are trying to answer before I can even get the question fully asked or are not completely reading the questions in the posts.
Case in point, my original first post said I what ammo I am using, then the first expert reply asked what ammo I am using...
In my first original post I mention that I am using the formula for calculating front sight height, then I get a reply from the expert saying "hey, you ought to try out this formula that I've been using for years...
In my post above I said that I have a 25, 50 and 100 yard range at my disposal, then I get your reply saying I should shoot on a 200 yard range...

I don't at all doubt the knowledge base of some on this forum it just seems like there's some kind of race to give me an answer, any answer, before pausing a sec to consider exactly what I am asking.

So far BrianDick and Parashooter have given me the most useful information. That since I am using lighter ammo I cannot rely on the actual numbered marks on the sight to be accurate and that I must memorize or record clicks from zero or from bottoming out to establish ranges that I wish to shoot on. This is how I have set the sight on my AR15. Establish a 25/300 RIBZ and then -4 clicks for 50/200 and -6 clicks for 100 yards.
My original questions were to check the accuracy of my math on front sight height formula, see what difference there would be in the 174 grain vs 150 grain ammo, and confirm my suspicions of a trajectory of zero minus 3 clicks at 100 yards after a zero was established.

Now judging from the previous replies to my posts I suspect the next one in line will be from an expert telling me that I can't attach and AR15 sight to my Enfield.

[CINDERS]

Here ya go bloke a Ballistic chart for you to peruse happy shooting.

[Parashooter]

Why do you want to fool with the front sight height at all? You can do this elevation zero job using only the rear sight - remembering that the markings are meaningless with non-standard ammunition.

If I understand your description, you are hitting 4.5" low at 50 yards (let's assume that's below point of aim since you don't specify your aiming point or hold). All you have to do is raise the rear aperture enough to put the POI 1/4" above POA at 50 yards. (That should be some 9 or 10 clicks from wherever it was when you shot the 4.5" low group). POI should then be on POA at 100 yards and 5" low at 200. Add 2 to 3 clicks to bring POI to POA at 200 yards. These calculations are based on Prvi's published MV of 820m/s for this load, front sight .8" above bore axis, and a BC of .375.

Here's a little graph of the trajectory with 100-yard zero. Click on it and it should become big enough to read.

Attachment 54093

If you use a 6:00 or other below-center hold, add enough elevation to compensate for the difference between POA and target center.

[muffett.2008]

Or maybe just get a target rifle zeroing target and do it all from 25yds.
Attachment 54115

[CINDERS]

BD and Para are right and it is what I have done for all my 303's for what ever load I want to use look up the little blue book and adjust accordingly despite the indicated range on the ladder on my No.4's or rear sight on the Mk III's just means some range time on a decent range with various loads you may use.

You cannot speculate or guestimate the trajectory of your reloads because we do not have access to MK VII cordite or the projies with the correct BC to match so hence forth all SMLES mine included the sight will be close with some loads/bullet weights like the SMK 174 and the Highland 174.
And if you mix and match for different matches like I do light loads for 100yd when standing and cranked up when we get back to 600M as there is no power factor involved I use Hornady 150gns up to 300M as they are .312" better obturation with the larger Dia and being a SPFB where as the SMK are .311 or I have seen some at .310.5.
We can shoot from less than 5yds ~ 1000yds but have yet to try a 303 at the 1000yd distance, like I said have fun.

[CINDERS]

Wihat difference will it make that I am using 150 grain soft point boat tail ammo?

What type of ammo PRIVI, Highland, Hornady, Sellior Belliot, Remington have you chronied your reloads or are you guestimating from short range tests, have you got access to chronograph so you can map the trajectory from the bullet velocity!!
The pistol club should have one we had one at ours in the club house also one at our rifle club for members to utilise should they wish to.
And to be fair to the rest of us bloke that are trying to assist with your quest to get the POA=POI that's as far as you go explaining what type of ammo you are using are you throwing the 150gn SPBT at the target by hand I still see your sniping at those that are trying to assist you and I would not really expect information from one forumer to be coming your way after you had 2 cracks at that person.
Me I do not really care what you do obviously there is no room in Texas for you to get out and pace or range find a 200yd distance to expound your theory on your required POA=POI what you will need is cases, primer, powder & projies loaded up, a nice day and a safe load in the rifle we are all just trying to assist you but range time and getting the results from a computer or slide rule are 2 different things. So good luck bloke in your endeavours because when it comes to the time to quickly get to a hold under at a close range you would have wished that you had given the time to fire over the 200yds you required cause a critter aint gunna sit there while you twiddle with your sights, it has to be known and instantaneous your decision to be automaticly computed in your noggin whilst the rifle is coming up to your shoulder if it is not already there having spotted the beastie.

I justified range time with my 308 APRS by hitting one of those pest things we have which was at full tilt (hopping) in a spotlight (just at the spots clear limit as we were using a red filter) at 150M whilst the APRS is sighted for 300M no time to dial the elevation turret bloke swing hold a tich under the known POI = lead, fire and follow through = 1 shot one kill

[Parashooter]

Let's at least pay a bit of attention to what has already been posted:

I am using 150 grain soft point boat tail ammo. Prvi partisan to be exact.

I'm fairly confident this means he is using factory ammunition, not handloads. The ballistics of this load are published on Prvi's website, so it's not hard to calculate a trajectory for him if he doesn't wish to do so himself.

Output from jbmballistics.com online calculator -

Ballistic Coefficient:	0.375 G1	Caliber:	0.311 in
Bullet Weight:	150.0 gr
Muzzle Velocity:	2690.0 ft/s	Distance to Chronograph:	0.0 ft
Sight Height:	0.80 in	Sight Offset:	0.00 in

Range	Drop	Drop	Velocity	Energy
(yd)	(in)	(MOA)	(ft/s)	(ft•lbs)
0	-0.8	***	2690.0	2409.7
50	0.3	0.5	2570.5	2200.3
100	-0.0	-0.0	2454.1	2005.6
200	-5.0	-2.4	2230.3	1656.4

What's hard for me to understand is why he wants to change the front sight - an exercise that would be necessary if his POI were too high with the aperture bottomed out, but isn't needed when his POI is low. Because I seldom shoot genuine Mk7 ball, it's very handy to have some wiggle room in both directions (up and down), to adjust for different loads. The last thing I'd want is a front sight so short that I had no downward adjustment available to zero a different load that impacts higher.

He has correctly calculated the amount of sight change needed to bring his POI up 4.5" at 50 yards:

I came up with 28.5 x 4.5 = 128.25 / 1800 = .07125

But it seems to me he's applying this to the wrong end of the rifle. Running the aperture up 9 clicks (.008" per click times 9 = .072") will have the same effect. Adding another click will give the appropriate elevation to put him near center at 100 yards (with a center hold) and 2 or 3 more will give close to the 2.4 minutes needed to adjust for the 5" drop from 100 to 200. If we can just persuade him to stop thinking about the graduations on the leaf, he should do OK.

[Peter Laidler]

See what I mean about keeping it simple chaps!
Foresight INTO the error, backsight OUT of the error is all you need to know in my humble experience

All I can say is that I'm glad that there's not a similar discussion to this regarding the No2 revolver or the old No2 Browning! There it was '.....well aim off a bit then......'

[Patrick Chadwick]

I am not using the backsight as a zeroing medium. I am using the front sight.

Please do not take this as a personal comment, but as practical observations based on experience with long guns from a Napoleonic vintage musket through to a modern 6mm BR shooting machine, and a lot of what came between. That means everything from a howitzer-like trajectory to a very flat one indeed, and I have given up trying to make precision calculations for range changes, being happy if the correction puts the bullet in the black at the altered range. I realize that I am also partly repeating what has already been put quite precisely and in detail, so I shall put it quite straight and simply.

Be CAREFUL to compare like with like. If you are using a 6 o'clock hold, then you are applying a vertical offset of half the diameter of the target black between your actual POA and the intended POI.

If, for instance, you shoot with a 6 o'clock hold at 50 and then move the same size target out to 100, then the black now subtends half the angle in your sights compared with 50, so you are raising the POA by an amount equivalent to half the difference between the bottom of the black and the center at 50. That is quite a lot - in fact half of the apparent size of the black if you double the range - and this effect alone often means that a rifle that is in the black at 50 will also be in the black at 100 without any further adjustment. The POI may be higher or lower, depending on the height of the sights and the trajectory of the bullet. The same effect applies if you go from 100 to 200 with the same size of target black. Even if you use proportionally scaled targets to produce the same apparent size at all ranges, there is still the following effect:

CONTRAST CHANGES WITH DISTANCE*. Your judgement of the correct aim for a 6 o'clock hold is affected by the contrast between the blade, target white and target black. So shooting one-hole groups at 25 yards will still not enable a perfectly calculated correction for 200. And if you are using a center hold (generally not advisable with a blade foresight) then the contrast effect is even stronger.

Use 100 if you can, 50 if you must, but forget 25, where the "uphill shooting" deviation caused by the sight line being above the barrel center line is quite extreme.

Be GLAD that you have a +.075 foresight blade. I wish I had a couple myself. The vast majority of old service rifles were zeroed for a longer range and/or have foresights so worn down that you can hardly get on target at 100. As has been pointed out, the higher foresight gives you room for adjustment if/when you try out different loads. DO NOT SNOOKER YOURSELF BY REDUCING THE BLADE HEIGHT TO SUIT ONE LOAD AT ONE RANGE. You have a height adjustable backsight. Use it.


*And lighting conditions!

[Ridolpho]

All I can add to this is that Remington and PRVI both sell 174 grain FMJ loads that I've found to work pretty well with the existing (probably Mk VII) zeroing on all of the Lee Enfields I shoot with. For example, at a shoot last year, I grabbed a Lithgow No. 1 that I had never used and found the Remington stuff to be spot on out to the max 400m (450 yd) range used.

Ridolpho