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  1. #1
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    Default What size front sight do I need no4mk1*

    I have longbranch 1943 no4mk1* which one of these do I need to get .50 tall, measured from bottom of the -.015 base on it.
    3 BLADE, FRONT SIGHT, SPECIFY SIZE (-0.15, -0.3, 0.0, 075, 076, 114, 06, 03, 0.45, 1.9, 1.52) 2.00 ea.
    Would the .45 be it? how is it marked for measurement? I hate to pay $10 for shipping a $2 part especially if its wrong when it gets here. Thanks
    Touch The Cat Bot a Glove, Macpherson.

  2. #2
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    I don't quite get what you mean by .50 tall - that is a full half-inch and is a massive adjustment in a front sight.

    The No 4 sight elements all have the same blade height - about .145".

    It is the height of the base block which varies. The sight bases are marked depending upon how their base thickness varies from the standard size.
    On a No 4, the "0" marked sight is designed to put the top of the blade 1" above the centre-line of the bore. Sights varied in increments of 0.015".

    If you in fact need to increase your sight height by .050", you could go up three sizes (.045"), so -0.015 + .045 = .030" would probably be the one you want.
    Last edited by maxwell smart; 04-16-2013 at 02:57 AM.

  3. #3
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    I'm not quite clear on your question - and the 'sizes'you have quoted for the front sight blades are a mix of inches (thou') and mm.
    The proper military sight blades are only in thou' whilst commercial (later ones) are in mm.

    To identify which sight blade you need, shoot a 'reasonable' number of rounds to get an indication of POI vs POA, each sight blade change will incease / decrease the POI by 1.87" at 100 yards, so - if your POI is 3" low,then change your sight blade by two sizes.


  4. #4
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    [QUOTE=Alan De Enfield;2555725]I'm not quite clear on your question - and the 'sizes'you have quoted for the front sight blades are a mix of inches (thou') and mm.
    The proper military sight blades are only in thou' whilst commercial (later ones) are in mm.

    To identify which sight blade you need, shoot a 'reasonable' number of rounds to get an indication of POI vs POA, each sight blade change will incease / decrease the POI by 1.87" at 100 yards, so - if your POI is 3" low,then change your sight blade by two size

    I have a -.015 on it, it shoots 13 inch low at 100 yds, Kentucky hold over is about even with top of the holes for the front gaurd. I need what ever sight is closest to .50 total height from base of dove tail to tip top of blade. Make sense?
    Touch The Cat Bot a Glove, Macpherson.

  5. #5
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    I dont think any change of sight blades will achieve 13" change in POI

    There may be something more seriously 'wrong' with your rifle.

    Are you screwing the rear sight 'right to the bottom'?

    After having read Peters notes, identify which block-band you have,maybe you can then find a higher one and solve your problems.

    Here is some interesting information from Peter Laidler :

    A bit of heavy weekend reading for you.......................
    There has recently been some too-ing and fro-ing correspondence about the sights
    used on the No4 rifles. Maybe it’s time to open up a few little previously unknown or
    certainly not fully understood points.

    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……………

    THE No5 RIFLE

    If you have a No5 rifle, then a similar situation arose there too but the situation was
    even more dire as the reflected line of shine certainly DID cause problems. So while
    the No5 blades were all split blocks, the;
    Mk1 split block blade for the No5 equates to the Mk1* blade for a No4 rifle
    and the Mk 2 split block blade for the No5 equates to the Mk3 blade for a No4 rifle.
    There were different part numbers for the blades indicating that there were subtle
    differences between the No4 and No5 types. Quite what the differences between the
    blades were on paper didn’t manifest its way to us as young Armourers in Malaya! We
    used split block ‘double undercut’ blades on every No5 we zeroed of course, but they
    all came from the same tubs, regardless of whether it was a No4 or 5 blade. They all
    looked the same to us and we treated them the same too!

    But back to No4 rifles and the BLOCK band, foresight. Are you in for the long haul?
    Soon after the large late 40’s FTR programmes, it was established at Fazakerley that a
    large percentage of fully refurbished rifles were impossible to zero due to them
    shooting too high. Fazakerley sought to obtain a relaxation in order to use the +.090”
    and +.105” STEN gun foresight blades but already there were problems relating to the
    final inspection standards that I won’t go into. But the same problems were apparent
    outside the factories and Base Workshops, in service too so while the factories, FTR
    programme contractors and the large REME Base workshops were NOT permitted to
    use the higher Sten foresight blades, a relaxation was sought that they could be used
    at unit level (both high sizes) and Field workshop level (just the .090 size). But this
    was palliative and not a cure by any means. The answer was that where a rifle was
    perfect in every other way, then a Mk2 BLOCK Band foresight was available.

    The ‘new’ BLOCK, band, foresight was .030” taller, at .490” than the original Mk1
    block band, at .460” tall. This immediately, but invisibly, allowed for a further 2
    increases in blade height (……. think about it!). The new blocks can be identified by
    the figure 1H for the Mk1 split block or a 2H for the Mk2 solid block, marked on the
    rear sloping surface. But even these didn’t last long because they only allowed for a
    further two ‘invisible’ increases of foresight. The problem was more acute than that
    with thousands otherwise perfect No4 rifles stacking up in Ordnance depots unable to
    be zeroed So in an act of almost desperation in January 1954, two FURTHER
    foresight block bands blocks were introduced. These blocks were heightened by a
    further .030” to .520”. So we have the original block band height of .460”, the 1949
    increased height to .490” then the 1954 block band with a height of .520”. At a stroke,
    we now have a block band foresight that allows the highest blade ( the .075”…., don’t
    forget that anything higher was for the Sten gun) to be, in effect .135”……… which is
    1.135” above the centre line of the bore

    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!
    Jeeeees, we had to learn, know and put into practice all of this rubbish! The most
    astute of you will now be looking at your ‘original, untouched since the factory’ rifles
    to see if it has the higher foresight block band fitted. Only a post 1949 made rifle will
    have a block marked 1H or 2H and only a post 1954 made rifle will have a block
    marked 1 or 2 on the rear surface as original. Before that, they were bare!
    But there’s a little more……………. Our acceptable zeroing standards state after
    zeroing, the blade of the foresight will overhang or be level with the edge of the
    foresight block. If the edge is inboard of the edge of the block, then it indicates that
    something is wrong with the rifle. BUT, it was discovered that while the UK made
    foresight blade bases were .38” wide, due to a tolerance error, the Canadian bases
    were .43” wide. Without going into the technicalities, a rifle fitted with a Canadian .
    43” wide base could fail the zeroing criteria unnecessarily. So these Canadian .43”
    wide blades were all declared obsolete and withdrawn.

    There, a little bit about a previously unknown feature of the No4 rifle! Not a lot of
    people know that!

  6. #6
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    What sight picture are you using?

    6 O'clock hold or centre aim?

  7. #7
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    If your gun is shooting 13 inches LOW at 100 yards, then your front sight correction needs to be a lower one. Since you already have a -0.015", there is only one more available lower size in the range, so you will not be able to adjust it to where you want.

    One possible solution is to crank your rear sight up 13 clicks from where you have it now, and see where your point of impact is then. You might have to just accept that this is the sight setting you need to use at 100 yards for that particular ammo.

    Unless your ammunition matches the ballistics of the Mk7 military round, the range markings on the rear sight are only a guide anyway.

  8. #8
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    Quote Originally Posted by maxwell smart View Post
    What sight picture are you using?

    6 O'clock hold or centre aim?
    Looks like I'm 13 inch high with 300 sight and 19 high with 600 flipped up. I'm shooting 150 grn reload at about 2450. Current sight picture has front sight block/base sitting on bottom of rear sight so front sight and rear bottom radius matching holding at 6 o clock of target.
    Touch The Cat Bot a Glove, Macpherson.

  9. #9
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    Quote Originally Posted by rex clayes View Post
    Looks like I'm 13 inch high with 300 sight and 19 high with 600 flipped up. I'm shooting 150 grn reload at about 2450. Current sight picture has front sight block/base sitting on bottom of rear sight so front sight and rear bottom radius matching holding at 6 o clock of target.
    My bad read target upside down in first post sorry for confusion. Thanks
    Touch The Cat Bot a Glove, Macpherson.

  10. #10
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    Ahhhh - 300/600 flip sight.

    What range are you trying to 'zero'at ?

    Replace it with a Mk1 micrometer sight to start with, wind it down tothe bottom and then start looking at front sight blades.



    Ok-too many variables at the moment:

    1) Replace rear sight and wind down to 200yds
    2) Use MkVII ammunition (or Prvi Partisan 174gr FMJ is close)
    3) Zero at 100yds

    POI should be 3" high.

    Any variation on this then start playing with the front sight

    Alternatively - keep the Mk2 rear sight but accept that the POI is 6" high at 100yds (as per the table I posted above), If you are 13" hight then you need 7" of adjustment (13" - 6" =7") therefore you need about 4 increases in blade height , ie probably a 0.045 blade (-0.015 to 0.00 to+0.015 to 0.030 to 0.045)

    Hopefully you follow my thinking
    Last edited by Alan De Enfield; 04-16-2013 at 11:00 AM.

  11. #11
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    Quote Originally Posted by rex clayes View Post
    Looks like I'm 13 inch high with 300 sight and 19 high with 600 flipped up.
    With that rear sight you should have your bayonet fixed at 300 yards.
    "a rifle should be kept in every cottage in the land."

  12. #12
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    Quote Originally Posted by Beerhunter View Post
    With that rear sight you should have your bayonet fixed at 300 yards.
    I just read that else where about 10 minutes prior to your post. Another thing I never knew about this gun. Thanks everyone for the info, I love this forum. All good info no crap. I learning a lot
    Touch The Cat Bot a Glove, Macpherson.

  13. #13
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    rex clayes, I have the 1.52 and 1.90 new front sight baldes. I can send them to you for $6 no shipping charge. I also have the Mark I and Mark II, and the Jungle Carbine (800 meter )rear sights. Let me know if you're interested.

  14. #14
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    Quote Originally Posted by rex clayes View Post
    I just read that else where about 10 minutes prior to your post. Another thing I never knew about this gun. Thanks everyone for the info, I love this forum. All good info no crap. I learning a lot
    OK looks like I would like to be +.12 higher than where I am now and it's marked -.015.
    i may be interested in buying a sight too, so maybe
    Touch The Cat Bot a Glove, Macpherson.

  15. #15
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    Quote Originally Posted by Alan De Enfield View Post
    Ahhhh - 300/600 flip sight.



    Is it just me, ir does anyone else find it confusing that the Mark 3 sight is stamped "Mark II", and the Mark 4 sight is stamped "Mark 3"?

    I always figured the British had things more in hand than that.

  16. #16
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    Quote Originally Posted by Ronbo6 View Post
    Is it just me, ir does anyone else find it confusing that the Mark 3 sight is stamped "Mark II", and the Mark 4 sight is stamped "Mark 3"?

    I always figured the British had things more in hand than that.
    Not at all.
    The Mk11 on the Mk3 sight refers to the sight body and not to the complete sight - similarly with the Mk3 marked Mk4

    Simples !!!

  17. #17
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    Quote Originally Posted by Alan De Enfield View Post
    Not at all.
    The Mk11 on the Mk3 sight refers to the sight body and not to the complete sight - similarly with the Mk3 marked Mk4

    Simples !!!
    Still clear as mud.

    Is there ANY lack of interchangeability or SIGNIFICANT differences between the two sight bases (or anything other than the slide stop being on opposite sides, and the obvious bend in the catch)?

  18. #18
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    No. The design of the spring changed a bit.

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