No. 4 Rifle; Zeroing Instructions Data Inconsistency?

[Rick]

As I'm once again getting ready to make our range my second home as the last of the snow disappears, I am again distracted by the zeroing data for the No. 4 rifle being inconsistent when looking at the Canadian pams versus the Brit/Aussie pams that I have on hand.

I know this is mostly academic at this point, as Mk VII ammunition has become pretty much as easy to find as unicorn poop. But to summarize what is aggravating me so much, the Canadian pam Shoot To Live from 1945 is my Canadian resource.

The later 1991 and 2002 Canadian pams for the rifle concerning operating instructions (curiously) have no references to zeroing instructions. (As well, I thought the Canadian military coming up with "Shoot To Live" as the appropriate title for training infantry to kill with the rifle was a product of modern Canadian governments).

Because all training centres have not the complete facilities for zeroing rifles
at 100 yards, the methods of zeroing have been made available for both the
30-yard and 100-yard targets, although the latter is better. In either one
if you aim precisely at the point of aim, the sights should cause the bullets to
strike the 30-yard target 2.25 inches above the auxiliary aiming mark's base
and if it were to continue to the 100-yard target it would strike 8.5 inches
above the auxiliary aiming mark's base.

Should it continue on to the 300-yard target in the distance, it should fall
directly upon the aiming point.

The Brit's Precis No. SA/19A from 1950:

In the case of Rifle No. 4 fitted with a Mk 2 Backsight, the apertures of which
are sighted for 300 and 600 yards, the Rifle will be zeroed using the 300 yard
yard aperture with a Bayonet fixed.

So: the wartime Canadian pam says the No. 4 rifle with a 300 yard aperture will have a POI +8.5" at 100 yards when zeroed. British pams say a No. 4 rifle with a 300 yard aperture will have a POI of +6.0" at 100 yards when zeroed.

+8.5" versus +6.0" at 100 yards - that's a HUGE difference. Doing some quick tests in a ballistic calculator shows that the zeroing information from the Brit pams is almost certainly correct, while there's no way the Canadian information can be correct.

Am I missing something here in what I see as such a huge discrepancy?

I would think Canadian infantry NCO's assigned to be SAIs at the battle schools, taking recruits through the process of zeroing their rifles would immediately realize that using this data to zero at 100 yards did not get the expected correct results when firing afterwards at 300 yards.

And is there a Canadian pam for the No. 4 rifle published after WWII that contains zeroing instructions that I'm not aware of?

[Alan de Enfield]

Could it simply be the method of training ?

The Brits used the 6 o'clock hold for the POA (3" below the 'bull' ?)

From your picture the Canadians use the 'bull' for POA

[muffett.2008]

Or maybe it's the difference between the Brit Cordite round and the Canadian Nitro Cellulous one.

[Surpmil]

Without going and getting "Shoot to Live" off the shelf, does it describe zeroing as to be done with the bayonet fixed as you state the UK pamphlet does? If not, that might account for the difference in MPI vs. POA?

I'll see if I can get access to a post-war Canadian manual that describes zeroing the No.4.

[Rick]

I'll try this reply on my phone while cooling my heals in a waiting room.

First, thanks for the input:

First, both pams require rifles be zeroed with bayonet affixed, and rear sight be used with 300 yard aperture. (After 30 years in the military as a Death Tech, much of that on regimental rifle teams and a lifelong recreational and competitive shooter, I have always been curious as to why you would zero at 300 yards with bayonet affixed. Not much hand to hand quarreling that goes on at those distances. The shift of POI at ranges where you would have bayonet fixed would be irrelevant. We didn't zero our FNs in that manner)

Without my wartime Brit and Aussie Pam's here with me, from memory they specify the same data for zeroing as the 1950 Armourer's data. So it wouldn't appear as though any difference between cordite and smokeless would be a confounding factor.

Furthermore, if the same MkVII ball round leaves the muzzle at the same velocity, whether it got that MV from cordite or smokeless isnt going to make much difference.

Aside from all that, if there's a .pdf copy of a Canadian Pam's between the 1945 "Shoot To Live" and the 1991 verson of the No.4 Pam's which I have, I would like to see it out of curiosity.

I'm equally curious that there isn't any zeroing sections in the 1991 and followup 2002 pams.

[Bindi2]

Rick
I have never been able to match Cordite and Nitro loads on the range chart with the rifle sight markings at the same FPS. We had to make our own dope sheets.

[Rick]

I have never been able to match Cordite and Nitro loads on the range chart with the rifle sight markings at the same FPS. We had to make our own dope sheets

Unless I've forgotten, I don't think we were ever issued Mk VII ammunition from the DCRA that was cordite; I imagine it was all used up by that point, 30 years after the WWII ended and 20 years after Korea. By the time I enlisted, the No.4 had been replaced by the C1 FN FAL, so I had no military experience with the rifle.

That aside, we know you have to adjust your come-ups at longer ranges due to the differences between lots of ammunition. But perhaps more specific to the question, a couple of things:

1. With all the detail provided in the Brit military pam, if there was a significant amount of ballistic difference for the average infantryman between the original cordite and then after the ammunition was loaded with smokeless, I would expect that at some point in the Armourer's pam there would have been a notation on zeroing differences when cordite was being used and when smokeless was used. What pams and material I have read is silent on any significant differences.

2. A 2.5 MOA difference at 100 yards between the two sets of zeroing data is an enormous amount that I doubt the difference between cordite and smokeless could potentially explain.

3. If you try getting a grip on how such differences could be possible, pick your ballistics software of choice, give the Mk VII round a G1 B.C. of about .467 and a MV of about 2440 fps. Then look at the manipulations to muzzle velocity, etc you have to make in order to produce a ballistic result where POA=POI at 300 yards - and a height above line of sight at 100 yards that is 8.5".

On the other hand, the zeroing data provided in the Armourer's precis is pretty much bang on when fed into a ballistics calculator. The Canadian data in the 1945 Shoot To Live just does not fit.

My assumption is that I am missing something, somewhere, but the Canadian zeroing data just doesn't fit.

[Bindi2]

The bit you are missing is the difference in barrel harmonics between the two charges.

[Rick]

The bit you are missing is the difference in barrel harmonics between the two charges.

Thanks for the suggestion. But if that's so, the authors at Higher Niner of the various nations' pams, the 1950 Armourers' Precis, Reynolds, et al similarly also didn't notice the difference in barrel harmonics between the two charges in any version of the rifle.

None noticed sufficiently to even making mention of a significant difference in barrel harmonics between Cordite and NC loads, resulting in conflicting different zeroing data being required as in the Canadian Shoot To Live, based on whichever type of propellant was loaded.

As NC apparently was first introduced at the end of WW 1, and Cordite loaded ammunition was still in the supply system through WWII and then Korea, there is no certainty that a Commonwealth nation whose troops were in battle could be exclusively supplied with either Cordite or NC based ball ammunition to match whatever the troops' rifles were zeroed with prior to being sent into battle.

And a 2.5+/- MOA difference in zeroing is well over the difference of a single change in front sight blade height. So I would presume that Higher Niner, the ones developing and updating the pams throughout the service life of the rifle would have taken such a significant difference into account - even if only a simple notation somewhere within at least one of those publications, whatever version of the Lee Enfield it was attached to.

To fuel my academic curiosity about the two very different zeroing specifications, I have a range document from inside the Canadian Rangers with this related to zeroing their No.4 rifles:

LE Sites are calibrated to 174gr Spitzer Point Flat Base Mk7 Ammunition. Rangers are issued 175gr Spitzer Point Boat Tail Mk8Z Ammunition... Desired Point of Impact: 8.5" above the point of aim.

If Mk8z ammunition manufactured by IVI (or whoever in Canada) in the 1980's for the Rangers is in fact correct, at the suggested velocities for Mk8z ball ammunition, you would expect an even flatter ballistic parabola, and an even LOWER height above point of aim at 100 yards to obtain POA=POI at 300 yards.

[there's some confounding factors in these instructions in that the paper instructs zeroing at 100 meters, not yards, for a zero at 300 meters, not yards. And of course, with their issue sights calibrated for yards, I haven't bothered yet to see if a ballistic calculator says that a +8.5" POI works when sighting using metric instead of yards. I think a calculation of those ballistics, even with 300 meters being longer than 300 yards, you will still be lower than +8.5" at 100 meters to be zeroed with the 300 yard aperture at 300 meters.]

A shooting/rifle obsessed friend just retired as the RSM of his unit, and promptly joined the Canadian Ranger patrol nearest him. The Lee Enfield has been gone for a couple of years now, but I'm going to ask Gary if he can prowl what they have in the way of pams to see if they have anything there that relates to thus point of curiosity.

I also know Russ Meades as an acquaintance from way back in the day when he arrived here from the UK and enlisted in the Canadian military. Russ was pretty keen on shooting back in the day, and he ended his career decades later as the officer in charge of the Canadian Rangers; perhaps he can shed any light on it.

And finally, my brother retired from 30 years working at BATUS as a civilian whose working days were spent working beside British REMEs on the Challenger tanks and everything else mechanical that moved. He told me yesterday that one of the REMEs who stayed here is a Lee Enfield obsessed rifle nut, a good friend of his who I helped secure the recovery of a Land Rover (but why????), found multiple NATO documents on their military version of the DWAN that he printed out, which might relate to zeroing specifications. So perhaps there is something there as well...

Again, at this point it's purely an academic curiosity now that all the worthwhile Mk VII seems to have disappeared forever. But I do find a 2.5 MOA difference at 100 yards while zeroing these rifles to be interesting, with the Canadian disagreement with the other Commonwealth pams relating to zeroing this rifle.

Thanks again for the suggestions!

[Alan de Enfield]

As NC apparently was first introduced at the end of WW 1, and Cordite loaded ammunition was still in the supply system through WWII and then Korea, there is no certainty that a Commonwealth nation whose troops were in battle could be exclusively supplied with either Cordite or NC based ball ammunition to match whatever the troops' rifles were zeroed with prior to being sent into battle.

Cordite was used throughout the 'life' of the Lee Enfield and there are a number of period documents exlaining why the rifles should not fire ammunition of both types (Cordite & Nitro cellulose)

One example :

'Regulations For Army Ordnance Services', Vol.3, Pam.11A (1949) comments:-

APPENDIX 15

USE OF .303-IN CORDITE AND N.C. AMMUNITION

1. The action of Cordite propellant in the barrel of a .303-in. weapon is quite different from that of N.C. propellant.
Cordite gives a rapid build-up of pressure with great heat, leading to pitting and erosion of the chamber end of the barrel.
N.C., however, gives a more gradual build-up of pressure with less heat, and this in turn gives uniformity of barrel wear from chamber to muzzle, the amount of pitting and erosion being greatly reduced.

2. With Cordite propellant, set-up of the bullet is most pronounced and even when the chamber end of the barrel is well worn, the muzzle end still has sufficient rifling left to impart the necessary spin. As the wear advances up the barrel, so the accuracy of the weapon is progressively reduced.
With an N.C. propellant, set-up of the bullet is slow and by no means so pronounced, due to the more gradual building up of pressure. The barrel retains its original accuracy until wear reaches a critical stage, when a sudden falling off in accuracy occurs.

3. It can be seen by comparison with the effects of barrel wear that to use N.C. ammunition in a barrel which has fired Cordite will give serious inaccuracy in flight, whereas the use of Cordite ammunition in a barrel which has fired N.C. gives good accuracy, but serious changed the wear pattern of the barrel.
In the first case, i.e. a weapon which has fired Cordite ammunition the barrel will be eroded and fissured in the first few inches up from the chamber, the part in which obturation should occur. The poor set-up of the bullet, in the N.C. cartridge is not sufficient to give good gas sealing in such a barrel and the bullet does not, therefore, receive the maximum impulse. The resultant loss in velocity and instability due to lack of spin lead to a high degree of inaccuracy.
In the second case, Cordite ammunition fired from a barrel which shows uniformity of wear from firing N.C. ammunition, has an adequate reserve of set-up that ensures full gas sealing, with satisfactory velocity and spin. Unless the barrel wear is in a advanced stage due to firing a large number of N.C. rounds, there will be no immediate appreciable loss in accuracy. Furthermore, the decline in accuracy for Cordite ammunition will follow the normal gradual fall-off experience in weapons firing Cordite alone, as the wear at C of R progresses.

4. Trials have proved that even if only a few rounds of Cordite ammunition are fired from an "N.C." barrel, the ensuing accuracy life when N.C. is subsequently fired is reduced considerably. The occasional and restricted use of N.C. in a "Cordite" barrel will however, have little effect on its ensuing accuracy life for Cordite, although naturally the fire of N.C. will not be very accurate.

5. The effect of wear of barrels can be determined by firing shots through a paper screen at 100 yards. If, on examination of the screen, all shot holes are not perfectly round, then the barrel is no longer fit for use.
The danger lies in the fact that bullets fired erratically from badly worn barrels may overcome their instability in flight and take up a steady flight in the direction in which they happen to be pointing, with short-ranging and disastrous results if used for overhead fire. Except under these conditions of long-range firing there is no risk involved, though in normal range firing inaccurate fire will result.

6. The following instructions regarding the use of .303-in ammunition have been issued to users and are governed by stocks and types of ammunition and weapons in current use:-

(a) .303 in. Vickers M.G.s in M.G. Bns.

(i)Mk.8z only will be used for overhead firing.
(ii) Mixed belts, i.e. Ball, Tracer, A.P., etc., will NOT be used.
(iii) Any barrel which has fired Cordite ammunition will NOT be used for N.C.; barrels will be stamped “7” on the trunnion block and returned to R.A.O.C. through normal channels.
(iv) Barrel life for N.C. will be assessed by unit armourers using the appropriate gauges.

(b) .303 in. Vickers M.G.s in A.F.V.s.

Here the overhead fire problem is not considered; the range is usually less than is the case with ground M.G.s. tracer ammunition is required as an aid to fire control, and prolonged fire programmes are not envisaged. Special mixed belts of Mk.8z and Tracer are provided in boxes clearly marked “For use in A.F.V.s only”. The reduced life of the barrels is accepted.

(c) Light M.G.s.

Cordite ammunition normally will be used. N.C. ammunition, however, gives a relatively small flash at night and if the Bren is being used for a special purpose, e.g., on a patrol, its use is permitted.

(d) Rifles.

N.C. ammunition will not be used in rifles except in such circumstances as quoted in para. “(c)”
above, if necessity should arise.

7. Belt packed S.A.A. for M.G.s is packed in boxes which are clearly marked with labels or stenciling indicating its proper use. It will never be de-belted and used for practice purposes in L.M.G.s or rifles.

8. It must be noted that the above restrictions apply only to ammunition fired from British weapons. All American ammunition is N.C. loaded and their weapons are designed to fire it satisfactorily.


It is interesting to note that Lee Enfields that were authorised to use Mk8 (NC) ammunition had the barrel marked with an "8 in a circle"



See example #31