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Working on zeroing my No4 Mk2, was able to remove the original front sight but now I can't get a new blade in!
that front screw has been removed, I bought No4 blades but nothing seems to want to fit. Anyone have advice or is there some tool I'm missing? I can't even get them started into the dovetail.
Extract from an old post by PL on the No4 Front sights :
Let’s take the foresights first. For the No4 rifle, there were 4 distinct TYPES of foresight blade. The very FIRST was, naturally enough, designated the
BLADE, foresight. It came in eight sizes, from -.030”, -.015, 0, +.015”, +.030”, +.045”, +.060” and +.075”. These sizes (and I’m sure you all know this by heart…..) indicate the tip of the blade height below or above 1” of the exact centerline of the bore while the blade size ‘0’ is exactly 1” above the centre line of the bore ……, phew! Now for another misunderstood point. All of the actual BLADE heights are the same of approx .140” but it’s the .38” wide blade BASE (or stool) height that differs to make up the sizes. I know that some of you will say that this isn’t correct because ……… I know this and that’s because some of the commercial companies, including Parker Hale made their own variants including thinner widths, blow-up tyres and wind-up windows etc. BUT I’m talking about the Ministry of Supply/Army issue blades
This blade was followed by a later blade style so as a result, the first original blade was redesignated the BLADE, foresight, Mk1. The Mk1 blade is easily identifiable by having a SOLID base. This is because it was retained firmly in position, gripped by the split BLOCK, band, foresight. The split foresight block is closed, to grip the solid blade, by a reverse headed screwdriver. It is the REAR of the Mk1 blade that we ought to be aware of now, where the undercut/inward sloping blade part meets up with the block, which then slopes outwards towards the base of the block. So, the side elevation of the blade forms a side-on ‘V’ shape.
This rearwards and upwards sloping base could and did allow a line of reflected light to shine straight back into the shooters eye. Maybe not on the manicured ranges at Bisley but it certainly did in the bleak sunshine of Tunisia and Italy from where the complaints came
The next foresight blade was introduced as a result of efforts to cheapen the cost of the No4 rifle in 1941. This time, instead of using a split block, band, foresight and the reverse headed 4BAscrew, the block, band was left solid. But in accordance with good engineering practice and to maintain the required friction to hold the blade secure within the block band foresight, the BLADE base was manufactured with a split block. This split block blade was called the BLADE, foresight, Mk1*
The sizes remained the same as did the zeroing procedure, as did the side-on ‘V’ side elevation of the rear of the blade. It’s just that the block was easier and cheaper to manufacture. The new slot made very little difference to the cost of the blades because a), they were manufactured ‘biscuit-block (some call it chocolate block) fashion anyway and b), the addition of a simple slitting saw operation along the base was an almost academic addition and c), the original blades were still being produced anyway!
So there you have the earliest Mk1and Mk1* blades.
Now here is where we get a little more complicated. The Mk2 blade…………. The Mk2 blade was very similar to the Mk1 blade with its 8 sizes and its solid block base only this time, where the undercut/outward sloping blade part meets the base part, the base extends rearwards a small amount, then the BASE takes on an undercut inward sloping angle too. This immediately solved the reflected light problem because now, both the blade and the base reflected downwards. This blade was introduced as the BLADE, foresight, Mk2
If things were simple, the next blade would be designated the Mk2* but we don’t do simple…., we do complicated! So, the next blade became the BLADE, foresight, Mk3. As you might expect, the Mk3 blade was identical to the double undercut Mk2 but this time came with a split base to use in the solid block band foresight.
The earlier Mk1 and Mk1* blades were thereafter, obsolescent. Obsolescent but not obsolete so there are thousands of thousands still in service……………
So now we have a total of SIX BLOCK, band foresights.
The Mk1 and Mk2 original, the
Mk1H and 2H modified both .030” higher than the original, and the
Mk1 and 2 SECOND modified, now .060” higher than the original!
You’re not quite believing this are you? But help was at hand. The second block was pure duplication so was declared obsolescent. So that after 1954, only the first, original blocks and the third pattern, .060” taller were available from Ordnance stores. While the second pattern was obsolescent, you HAD to have the original, lower block of course in order to cater for those rifles firing LOW!
Then were the sight blades to suit.
Maybe you have got "correct" No4 sight blades but incorrect ones for your version of the block-band.
It usually starts in better from one side than the other (unless you were supplied with Bren gun foresights by mistake)
Dang, had no idea about this mess regarding the front sight blades. So if I'm following right for my mid 50s Irish contract I use Mk1 and Mk3?