Large error in Zeroing No 1 Mk III* at 25 yards - your thoughts, please?

G’Day Enfield Experts,

I have a zeroing issue and I’m stumped to understand how/what/why. Maybe your collective experience and knowledge may help? I have read the previous posts and articles on how to zero, how to adjust foresight blades and the like. This situation is beyond not following basic instruction.

I have a No 1 Mk III*, FTR Lithgow in 1956. Zeroing at 25 yards, the following 3 shot groups were observed:

Sights @200yd MPI +3.15” above POA
Sights @300yd MPI +4.13” above POA
Sights @400yd MPI +4.13” above POA

Foresight is 0.015” blade. Ammunition is Privi Partizan 174gr FMJ, MV 2460fps (published). While not Service Mk VII ball, I won’t agree that commercial or handloaded ammo will be this far out. I have recorded similar errors at 100m with hand loads known to be spot on in other No 1 Mk III* rifles I have. I appreciate that hand loads can be a little different in performance to commercial and service ball, but not this much difference.

Zero for 200yd, according to REME Armourer training pam, at 25 yds should have MPI 0.75” above POA, or at 100yds MPI 3” above POA.

The observed groups are touching, so my sight picture is OK. Sights are not.
No chance of adjusting POI by changing foresight blade, as highest blade is 0.03” and I’d need 0.69” or thereabouts!

What are your thoughts on correcting this conundrum? (Rear sight leaf is not loose, nor is any other component, headspace is between 0.064” and 0.072”)

I’d appreciate your views on how to approach this situation. Something is well out of whack…

'Fraid they can.
It is virtually impossible to duplicate the original cordite load, irrespective of what Muzzle Velocity you attain, the trajectory of the projectile will not match the sight graduations at all ranges.
If you achieve a match at the short ranges, it will be out at the mid and long, or if you zero for the mid's(600) then both the short and longs will be out.

If you note the MPI figures you quote for 300 and 400, they are the same, telling us that the trajectory is virtually flat...........a common thing with modern powders, but not possible with a cordite load.

You have two choices, either zero using Milsurp Ammo, or adjust your blade height to suit Modern loads and record your elevation settings for all ranges with your preferred load.

Zeroing at 25 will only give you a rough elevation, you need to check grouping at the ranges you will be shooting over.

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Originally Posted by muffett.2008

'Fraid they can.
It is virtually impossible to duplicate the original cordite load, irrespective of what Muzzle Velocity you attain, the trajectory of the projectile will not match the sight graduations at all ranges.
If you achieve a match at the short ranges, it will be out at the mid and long, or if you zero for the mid's(600) then both the short and longs will be out.

If you note the MPI figures you quote for 300 and 400, they are the same, telling us that the trajectory is virtually flat...........a common thing with modern powders, but not possible with a cordite load.

You have two choices, either zero using Milsurp Ammo, or adjust your blade height to suit Modern loads and record your elevation settings for all ranges with your preferred load.

Zeroing at 25 will only give you a rough elevation, you need to check grouping at the ranges you will be shooting over.

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Muffett,

Thanks for the response. Appreciate that Mk VIII and contemporary commercial rounds are different.

Having plotted ballistics graphs for stated projectile drop from manufacturer's data, the same thing happens to all projectiles: gravity and friction gets the better of them, in similar, but not the same extent. Hence, the drop at each distance interval is slightly different, as fully expected.

The 25 yard mark sees all projectiles rising. They start to turn (fall) around 50-60m when aiming for a 100 yard 'zero' (but accept that this is theoretical, as the leaf is not graduated for 100m, and the POA at 6 O'Clock should still be 3" or thereabouts high). I'm wondering if the similar observed figures at 300 and 400 leaf elevation is partly to do with the relative flat trajectory of the rounds? Though that doesn't give a satisfactory explanation when considering there is still a shift of the leaf between 300 and 400 yards. You are right, of course, that only by looking at grouping and measured fall of shot at required distances, say 300 and 500 yards, would there be a direct relationship to be relied upon.

The confusing issue is , in previous target sessions, when off the bench using same factory ammo I cannot get consistent strikes on a standard 100m target at 100m with this rifle, and need to revert to a 200m target at 100m to actually hit and be able to measure (based on consistent 6 O'Clock aiming point). Curious, when that same ammo is used in another No 1 Mk III* that manages to hit around the 3" high (or thereabouts) on a 200 yard sight setting. The issue is not explained by those combinations. Now noting that Mk VIII is not the same as current powders, I'm not seeing the logic to a 9.5 MOA difference in MPI for this rifle versus a similar Lithgow Mk III* with the same ammunition. One MOA, I'd accept as a variation due to age, wear, difference between round components, but not 9.5.

Adjusting sight elevation still seems to be a long way off a likelihood.

The question remains open.

I'd suggest you check both rifles with a chronograph, you will probably find a fair variation in velocity between the two, making any guestimate of accuracy irrelevant.
Due to wear, throat erosion and variations in chambers, the likelihood of two milsurps of this vintage printing a similar pattern would be like winning the lottery.

It strikes me from thread 3 that your rifle isn't so much out of zero but inaccurate as alluded to by Muffer. When we release them from workshops we test them for accuracy and NOT zeroing - although it's fair to say that they're sort-of zeroed*. I think that it's the accuracy pattern that you need to concentrate on correcting.

* Anyone who has seen a sniper rifle returned from workshops or issued from new will have a note attached to the paperwork that states words to the effect 'SNIPER RIFLE; NOT ZEROED (or unzeroed?) FINAL ZEROING IS THE RESPONSIBILITY OF THE END USER'

Quote:

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Originally Posted by Peter Laidler

I think that it's the accuracy pattern that you need to concentrate on correcting.[/B]

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Thanks Peter, ballistics, sight settings aside, I really feel I need to ask better questions to get to the bottom of this.

Appreciate the ideas and thoughts as offered.

Have you at least tried a higher fore-sight?
Is it possible there's excessive up pressure at the nose cap end of the stock?
With the variations in wartime manufacturing and the age and wear of these rifles, gun to gun consistency is not an exact science any more (if it ever was).
Is the zeroing difficulty a new thing with this rifle? Have you changed anything?

Quote:

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Originally Posted by harry mac

Have you at least tried a higher fore-sight?
Is it possible there's excessive up pressure at the nose cap end of the stock?
With the variations in wartime manufacturing and the age and wear of these rifles, gun to gun consistency is not an exact science any more (if it ever was).
Is the zeroing difficulty a new thing with this rifle? Have you changed anything?

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G'day Harry,

Great questions, thank you.

In the past I have noticed poor accuracy from this rifle, before but that was over 20 years ago (a little hiatus in my shooting...) Back to now, with better knowledge, better equipment and understanding, I'm getting very poor results. I have not yet stripped the furniture to see if there is definitive pressure/wear points.

Am thinking of re-working the furniture to remove the Tru-Oil finish. I am thinking of soaking both inside and out in linseed oil as part of the finish, to ensure there're little likelihood of drying/seasoning. I don't think it is the likely problem though. I haven't run a paper around the barrel from reinforce to muzzle yet. Recognise I need to.

The grouping on the test target indicates consistency, which is an excellent outcome. Inaccuracy through random shots would tell a different story. I do think I'll need to build up a foresight blade as part of the solution.

Really good, and helpful questions. Well thought out and helpful, my thanks for your consideration.

If the rifle is shooting large groups; you mention 9,5 MOA. Then you need to strip it and inspect it properly. I had a similar issue with my No1 rifle when I first got it; it was shooting 6" pattern's at 50 yards. (12 MOA).
I had several issues to overcome. Worn muzzle, poor fit at the recoil lugs, lack of up pressure on the barrel and some interference contact on the barrel. The wood was later BSA production; but had not been properly fitted. Having spent some time going through everything; thank's in part to Captain Laidler's articles. It shoots close to 2MOA. The errors now come from the shooter not the rifle!

some bullets only begin to stabilize once the get further down range

do you reload?