No. 4 Rifle; Zeroing Instructions Data Inconsistency?

As per the attachments to the first post in this thread "Shoot to Live" gives the MPI as 8.5 inches +/- 1 inch above POA at 100 yards. The "+/-" would seem to be the important point.

What if any range of variation in MPI at 100 yards is indicated in the UK manuals?

If the MPI is given as 6.5 inches presumably the range of variation would be 5.5" to 7.5"?

The Canadian range of variation is given as 7.5" to 9.5" so one can see the two(?) estimations presumably in a sense meet at the 7.5" mark?

The 2 inches of vertical variation provided for in "Shoot to Live" probably reflected a variation observed in actual range firing based on variations in rifles and ammunition.

My copy of "Shoot to Live" makes reference to the attack on Cherbourg in "the late summer of 1944", so the manual was presumably written or revised in late 1944 or sometime in 1945. Canadian troops in Europe were issued ammunition and rifles from British ordnance stocks so rather than a consistent quality of rifles and ammunition from Canadian sources, they could be issued any rifles and ammunition from any factories, British, Canadian or American. I have a Savage Mk.I* here which has the "US PROPERTY" barred out and several C Broad Arrow stamps for example. So estimations of what rifles and ammunition would do had to provide for variations in quality and consistency.

Both manuals agree that the MPI and the POA should coincide at 300 yards?

On page 198 it is stated: "It must be remembered that the recruit who has had his rifle zeroed at his basic training centre has only a roughly corrected weapon". It is also stated that some training centres would have only 30 or 100 yard ranges available, so the implication is clear that the 30 and 100 yard zeroes were preliminary to later zeroing at longer ranges. Was a final zeroing at 300 yards arranged before embarkation for theatres of operations? It would seem likely given the emphasis on rifle skills and accuracy which comes across in the 240 pages of "Shoot to Live".

On page 194, it is stated in upper case: "ALL ZEROING MUST BE DONE WITH BAYONET FIXED AND WITH THE BATTLE SIGHT OF WHATEVER MODEL OF BACK SIGHT IS ... AFFIXED TO THE RIFLE."

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Originally Posted by Surpmil

On page 198 it is stated: "It must be remembered that the recruit who has had his rifle zeroed at his basic training centre has only a roughly corrected weapon". It is also stated that some training centres would have only 30 or 100 yard ranges available, so the implication is clear that the 30 and 100 yard zeroes were preliminary to later zeroing at longer ranges. Was a final zeroing at 300 yards arranged before embarkation for theatres of operations? It would seem likely given the emphasis on rifle skills and accuracy which comes across in the 240 pages of "Shoot to Live".

On page 194, it is stated in upper case: "ALL ZEROING MUST BE DONE WITH BAYONET FIXED AND WITH THE BATTLE SIGHT OF WHATEVER MODEL OF BACK SIGHT IS ... AFFIXED TO THE RIFLE."

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At least in all factories under British control / management every rifle was tested and zero'd (without a bayonet fitted) as follows :


SMLE TESTING
For the SMLE All rifles were tested for accuracy by the Small Arms Inspection Department at 100ft, and 10% were also tested at 600 yds. All rifles were fired from a special mechanical rest, known as an Enfield Rest, and a special Telescope layer was used for laying an aim. The Enfield Rest was designed to simulate the conditions under which a rifle would be held when fired from the shoulder, and was provided with hand wheel adjustments for laying an aim. Trial shots were first fired and, if necessary the foresight was adjusted laterally, or replaced by one of a different height, until the shots on the target were within the required limits. Five rounds were then fired, and four of the five shots had to be contained in a rectangle 1 inch broad by 1½ in high. Rifle which failed this test were rejected. At 600 yds 10 shots were fired, nine of which had to fall within a 2 foot circle.

No 4 RIFLE TESTING
For the No 4 Rifle, the accuracy test was the same at 100ft ten per cent of all rifles were then fired at 200 yds when six of seven shots had to fall in a rectangle 6in x 6in , the point of mean impact having to be within 3 inches of the point of aim in any direction. Ten per cent of rifles fired at 200 yds were again fired at 600 yds when 6 out of seven shots had to be in a rectangle 18 inches x 18 inches the permissible deviation of point of mean impact being 9 inches up or down, or left or right. Two per cent of rifles were fired from the shoulder, ten rounds being fed into the magazine by charger and fired rapid to test “feeding up” and ejection. After these tests the barrel was inspected to ensure that there was no expansion in the bore or chamber and that it shaded correctly from end to end. (Was not bent)

No 5 TESTING
The firing test to which the No 5 rifle was subjected was the same as that for the No 4 at 100ft. It was not tested at 200 yds but 10 per cent were tested at 600 yards when the acceptance was ten out of ten shots contained in a rectangle 36 inches x 36 inches. Two per cent of the No 5 rifles were also submitted to the same functioning test as the No4 rifle.


Throughout World War 2 much of the accuracy testing was done by women shooters who quickly became proficient at the job. To speed up the procedure, the telescope layer was dispensed with, and aim was taken in the normal way through the back sight. The .1 inch aperture in the back sight was too large for easily laying a correct aim at 100ft, and a small spring steel adaptor was used.

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Originally Posted by Alan de Enfield

No 4 RIFLE TESTING
For the No 4 Rifle, the accuracy test was the same at 100ft ten per cent of all rifles were then fired at 200 yds when six of seven shots had to fall in a rectangle(sic) 6in x 6in , the point of mean impact having to be within 3 inches of the point of aim in any direction. Ten per cent of rifles fired at 200 yds were again fired at 600 yds when 6 out of seven shots had to be in a rectangle 18 inches x 18 inches the permissible deviation of point of mean impact being 9 inches up or down, or left or right. Two per cent of rifles were fired from the shoulder, ten rounds being fed into the magazine by charger and fired rapid to test “feeding up” and ejection. After these tests the barrel was inspected to ensure that there was no expansion in the bore or chamber and that it shaded correctly from end to end. (Was not bent)

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When describing "six of seven shots had to fall in a rectangle(sic) 6in x6in, the point of mean [main] impact having to be within 3 inches of the point of aim in any direction" the question would be how was "mean/main point of impact defined?

The edges of a 6x6 square are always 3 inches in any direction from the center*, ;) so any such mention of a "mean/main point of impact" is completely superfluous unless out of that six or seven shots a certain number were required to be more closely grouped than 6 inches(?)

Or were they just saying the same thing twice to better ensure it was (mis)understood??

Regardless, the 18x18 inch acceptable dispersion at 600 yards, effectively 3 minutes of angle, implies pretty clearly that many rifles, and whatever ammo was used to at least test them, were not of a high enough standard of accuracy to make the 2 inches at 100 yards under discussion here anything that could be relied on "in real life".

A guess could also be hazarded that if this 8.5" related to anything else, it might be that it was thought preferable in zeroing practice and perhaps in combat to have the actual fall of shot slightly higher than the POA?

* We'll leave out the matter of the distance to the corners, and why they stipulated a square and not a circle, as though a greater error in those directions than at the vertical and horizontal axes was somehow of less import ! :D

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Originally Posted by Surpmil

What if any range of variation in MPI at 100 yards is indicated in the UK manuals?

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I'm away from home putting my Griffon pup on some training birds over this Easter weekend, so I don't have my entire .pdf library at hand. But looking just at what I saved to my tablet, there is ARMOURERS' WING Precis No. SA/19A which implies the variation of MPI at 100 yards should be no more than 1.87".

In other words, no more distance than a change of front sight blade would result in then being closer to actual POA=POI. Each change of front blade size moves the POI either up or down 1.87".

If you were 2" in error from what POI should be, a change of sight blade should result in the POI being only .13" too high or low (as though that would be measured or measurable).

If your POI were 1.75" too high or too low, a change in sight blade would still result in a better zero. Now you'd be off in the other direction i.e. low instead of high or low instead of high, BUT now you'd only by off your desired POI by .1" of an inch.

By changing front sight blades, you should be no worse than +/- .9" inches from the desired POA=POI at 100 yards.

In the civilian world, many a front sight blade has given it's life to be put on a rifle and then the owner carefully dressed down the blade until they got the desired POA=POI with their desired load, at whatever distance they wanted one of the calibrations on their rear sight to be true at.

I would be surprised if more than a few regimental rifle teams DIDN'T do the exact same thing to get POI=POA as true as possible, rather than just "closest you can get with the front blades available".

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If the MPI is given as 6.5 inches presumably the range of variation would be 5.5" to 7.5"?

The Canadianicon range of variation is given as 7.5" to 9.5" so one can see the two(?) estimations presumably in a sense meet at the 7.5" mark?

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No. What you're visualizing is the overlap of the Figure Of Merit specified for the ball round/rifle combination by the Canadians versus the other commonwealth nations. Whether Brit or Canadian, whether the specified Figure of Merit grouping requirements are identical in size or different, you will ideally zero so that POA=POI is centered in the middle of the group within that Figure Of Merit.

You would adjust as best you could with the front sight height variations available to center on the middle of the group, whether the rifle put them all in a 2" group or a 4" group.

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The 2 inches of vertical variation provided for in "Shoot to Live" probably reflected a variation observed in actual range firing based on variations in rifles and ammunition.

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No. Or, no, I don't think so.

Remember that there are Figure Of Merit grouping standards for both the rifles and the ammunition itself no matter what Lee Enfield it ultimately ended up being loaded into out on the FEBA. Those Figures Of Merit are the limitations on what is allowed in variations in both the ammunition and the rifles.

I can't prove my opinion is right, but no, I don't think so. First, the author Johnson was an accomplished international Bisley/Palma competitor who had captained the Canadian team multiple times. That, and the focus of the book on SAIs effectively teaching the troops marksmanship doesn't lead to thinking the book was accepting of a completely different zero because that would somehow or other address mediocrity/lower quality rifles and ammunition.

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Originally Posted by Surpmil

Regardless, the 18x18 inch acceptable dispersion at 600 yards, effectively 3 minutes of angle, implies pretty clearly that many rifles, and whatever ammo was used to at least test them, were not of a high enough standard of accuracy to make the 2 inches at 100 yards under discussion here anything that could be relied on "in real life".

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No, they tested in "real life":

Proof of Ball and A.P. Cartridges

19. Firing proof will be carried out by the following method :-
The number of rounds taken I or the proof will be 40 from
each make and date of manufacture. Two targets will be used,
20 rounds being fired at each target. Should a further proof
be necessary {see para. 31), the rounds required will be taken
from the same box from which the rounds for the first proof
were selected.

20. The rounds will be fired on a calm day by a marksman.

21. {a) Rifle ammunition and ammunition of a calibre applicable
to both machine guns and rifles will be fired from a rifle at the
shoulder, using either a table rest or an ordinary table with sandbags
resting on it: or in the prone position using a sandbag cover. Only
the forearm and wrist will be supported by the sandbags.

22. The 20 rounds for each target wilt be all fired from the same
weapon and aimed at the same spot on the target, the object being
to obtain a group of 20 shots fired as nearly as possible under the
same conditions.

23. The target will measure 6 ft. X 6 ft. and be ruled with horiz-
ontal and vertical lines 6 in. apart. It should preferably be white
in colour.

24. Three rounds will be fired into the butts to warm the weapon.

26. A marking disc, 6 to 12 inches in diameter as required. should
be affixed to the target to indicate the point to be aimed at; one
or more sighting shots should be fired, and, if necessary, the posit1on
of the marking disc changed to ensure the whole of the rounds
being well on the target..

27. The position o! the sighting shots, which will not be included
in the "Figure Of Merit". may be signalled.

28. The position of the remaining rounds will not be signalled,
and the marksman will not vary his point of aim during the shoot,
irrespective of where the shots may strike the target.

29. The position of the shots on the target will then be shown on
the diagram (A.F. B202) and the "Figure Of Merit" will be com-
puted in the following manner:

(a) Find the horizontal measurement--measure the centre of
each hit from the left of the target.
(b) Find the vertical measurement-measure the centre of each
hit from the bottom of the target.

Each of the above measurements should be made with a rule and
plotted in corresponding position on the diagram.
(c) Find the mean point of impact; find the total horizontal
measurements and the total vertical measurements, then
divide the totals by the number o£ hits on the target.
The quotients give the "mean horizontal'' and " mean
vertical " measurements. Draw a vertical line at a
distance from the left edge of the diagram equal to the
mean horizontal measurement, and a horizontal line
at a distance from the bottom equal to the mean vertical
measurement. The intersection of these two lines is the
"mean point of impact ", i.e. the centre of the group of shots.
(d) Find the deviation of each shot; measure the centre of each
hit from the mean point of impact, and for each miss
allow 5 feet.
(e) Find the "Figure Of Merit": add together the deviations
and divide the sum by the number of rounds fired. The
quotient is the ·"Figure of Merit.''

30. The ranges at which the various calibres are to be fired, and
the mean Figures of Merit are :-
Calibre Range Figure Of Merit
·380-in. Ball 50 yards 9 in.
9-mm. Ball 50 6
·45-in. Ball 50 6
·45-in. T.S.M.G. G. Mk. 2z 100 15
·455-in. P.S.L. and Revolver 50 10
·303-in. Ball 500 12
·303-in. A.P. 500 16
7·92-mm. Ball 600 12
7·92-mm. A.P. 600 14
·5-in. Vickers Ball 500 15
·5-in. Vickers A.P. 500 18
·5-in. Vickers S.A.P. 500 18
·55-in. Ball, Mk. 3 500 14
·55-in. Practice P. Mk. 2 500 18
·55-in. A. P. 500 18 "
15-mm. 500 18

31. Should the appropriate " Figure of Merit " be exceeded,
a second proof should be taken in different weapons. Should the
" Figure of Merit " of the second proof exceed lhe limit, the
ammunition should be provisionally sentenced unserviceable, and
the firing proof diagrams should, in this case, be forwarded with
the results of proof.

So... a marksman firing his rifle from a rest had to verify the proof of .303 ball with two targets, 20 rounds on each, with the Figure of Merit being they grouped inside 16" at that distance

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A guess could also be hazarded that if this 8.5" related to anything else, it might be that it was thought preferable in zeroing practice and perhaps in combat to have the actual fall of shot slightly higher than the POA?

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This percolated down from the same people who ran the School Of Musketry at Hyanthe.

And from the perspective of an infantry section or platoon commander, I can't think of a possible reason that would be desireable, rather than a true POA=POI when the sights are set at the correct yardage to the target. If you're going to argue about sighting so that the result is like aiming off, you would rather rounds were low, where you would be more likely to see the fall of shot, rather than the rounds sailing over the heads of your enemy, leaving you nothing but a hole in thin air to not see.

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Originally Posted by Rick

No, they tested in "real life":

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I take it that the above information is taken from .......................

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Originally Posted by Alan de Enfield

I take it that the above information is taken from...

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No Alan... this one: Army Ordnance Services, Part 7, Pamphlet No. 11, Small Arms Ammunition (1945)

Pages 85 through 87.

It is interesting to see the comparison of the FoM for the "Long Rifle" rifle compared with the SMLE which were recorded in 1904 during the SMLE trials.

Comparisons were also taken with rifles used by other countries.

As you say Johnson was a highly experienced shot, and the whole book is testimony to his devotion to accuracy and, by implication that of his superiors. He makes repeated references to the absolute necessity of accuracy in order for fire - and the solder - to be effective. The group sizes shown in the book as examples of what was attainable or desirable are much smaller than the acceptance levels of accuracy for the rifles and ammunition.

In the last few days I happened to be going through my stock of used front sight blades and examining them under magnification and yes, there are numerous examples of minor modifications to the blades. It would only make sense when a minor elevation correction was needed, but the lateral deflection was perfect. A new blade inserted would require the zeroing be repeated in both axes and that would be time-consuming process. The book makes reference to the soldier and his rifle being sent to the armourer at the range for adjustment as part of the zeroing process of the individual rifles to each soldier. With 30 or 100 rifles to correct one can see how an armourer might file a little off a blade rather than replacing the entire blade and effectively recommencing the zeroing process. Whether that was permissible practice I have no idea.

The proof of ammunition is interesting and I photographed the entire Canadian manual for that a few years back when I had access to it, but that process was about testing the accuracy of the ammunition, not the rifles.

Perhaps your point in citing that was to establish the accuracy standards of the ammunition and by implication that of the rifles? Alan d’Enfield has posted the acceptable accuracy standards for the rifles from the UK manual, and probably the same standards were adopted in Canada. And of course “Shoot to Live” was not written specifically for Canadian-made rifles or ammunition.

Regardless, unless ammunition of a higher than usual quality was used to test the rifles at manufacture, the accuracy standards for the rifles incorporate the expected and accepted variations in the accuracy of the issued ammunition. Can we now say where one began and the other ended?

The 6.5" MPI over POA mentioned in the UK manual gives no range of variation such as the 2 inches mentioned in Shoot to Live, but of course a range of variation existed in fact. Presumably it wasn’t thought necessary to mention as the NCO’s involved were expected to understand that some variation was inevitable and the measurement therefore an approximation? The lack of attention to this in the text implies it was not considered of great importance. A formation on the ranges to give the rifles their initial zero would soon find out what the particular lot(s) of ammunition on hand tended to do, and adjust accordingly.

My first thought was the same as yours that having the MPI slightly over the POA would be less desirable in combat than the reverse. That would depend on what if anything had been learned about the aiming habits of soldiers: did they tend to aim low or high in combat? Whatever the case, I mentioned it merely as an idea to be considered.

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Originally Posted by Rick

ARMOURERS' WING Precis No. SA/19A which implies the variation of MPI at 100 yards should be no more than 1.87".

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What is the actual text and context? If this refers to the process of preliminary zeroing at 100 yards does it refer to the same variation which Shoot to Live gives as having an acceptable variance of 2 inches? Not a very large difference is it? 1.87" being effectively half of 3.75" one wonders about the context.

Regardless, Johnson describes this process as leading to a “rough zeroing”. Both manuals quoted refer to a MPI & POA coincidence at 300 yards. Shoot to Live states zeroes at 30 or 100 yards were preliminary and that the final zeroing would normally occur during advanced training and that this would be the zero that stayed with the soldier and his rifle throughout his service.

Logically the zero obtained at 30 or 100 yards would be mostly concerned with lateral error (windage). So considering that both manuals envisage a later final zeroing at 300 yards, the difference could amount to no more than where on the 300 yard target the respective authors preferred to see the first groups fired at 300 fall: higher or lower.

Perhaps you have already ruled out the types of targets used and the points of aim to be taken on them as variables that might explain this?

As we can see from this thread for example: h t t p s ://www.greatwarforum.org/topic/304772-external-ballistics-303-bullet/ there is plenty of debate about the rise and fall of Mk.VII ball and even about whether the formulas of the Textbook of Small Arms 1929 are entirely correct, so this variation between the two manuals is not so surprising in my opinion, nor significant given that the figures of 6.5" and 8.5" are merely points on a range of variation whose acceptable parameters overlap at 7.5 inches; whether that or indeed this whole matter has any significance in fact. ;)

(The TBSA 1929 is of course based on the No.1 Mk.III and the harmonics of its lighter barrel and action rather than the No.4 Rifle; the No.1 Mk.VI gets only passing mention.)

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Originally Posted by Surpmil

(The TBSA 1929 is of course based on the No.1 Mk.III and the harmonics of its lighter barrel and action rather than the No.4 Rifle; the No.1 Mk.VI gets only passing mention.)

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MkVI vs MKVII is another subject :
comparison in trajectories of MkVI & MkVII


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