Changes in Lapua D166 and D46 bullet design
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Thread: Changes in Lapua D166 and D46 bullet design

  1. #1
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    Default Changes in Lapua D166 and D46 bullet design

    Has anyone purchased Lapua D46 bullets recently? Have you examined the boat tail shape? While I've not seen this on happening on D46 yet, a couple of years back Lapua changed the D166 tail shape so that the classic rebate, which originally made the design accurate, is now more or less eliminated.

    While the chamfer probably aids bullet seating it also decrases contact area between the bullet and case neck. I think this might cause problems at least with D46 if you like to keep your COL as long as possible but you need to use magazine feeding when doing rapid fire drill for example.

    As a traditionalist, to the bone, I also disapprove the idea they don't make them like the used to! Maybe it's just me.



    Last edited by CH; 05-14-2017 at 02:33 PM.

  2. #2
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    I've been looking at my D46's and D166's under a 10X loupe. The D46's have a straight wall to the step, while the D166's taper into the step. My stock has been built up over the last eight years or so.

    I'm wondering if this is because no resizer die has the correct diameter for its expander. I use Forster dies, and got an expander that mikes .3085", but as far as I know that is the only die and expander combination that is correct for the D166. The taper at the step probably is designed to help seat the bullet in a case neck that has been resized more than 0.001" less than the bullet diameter.

  3. #3
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    Yeah, that explanation sounds plausible. The D166 lot I purchased in 2014 has the taper and measures 7.86mm. It is slightly thinner than the ones without the taper that usually are 7.87-7.88mm. Got to double check my older ones.

    After WW2, new D166 bullets weren't prodced until 1972 and the diameter tolerance was 7.88mm (0.04mm).

    Saw this picture of the D46 online and it looks like it now has the taper as well.


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    I have some D46 purchased last month. I'll take a photo.

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    http://i1260.photobucket.com/albums/...pszt00tu5o.jpg


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    Hi Les, thanks for the picture. Yours look like the original "D-31" type of boat tail, the way this bullet has been since it's introduction in 1931. No extra taper there. Someone might be able to tell the date from the label but I don't know how to do that.

    I ordered a 1000 pc. box of D46 but heard that Lapua is now out them and they won't be available again until mid-June. Those should be as new as ever.

    When absolutely splitting hairs, the current D46 doesn't seem to have quite as sharp tip than those made 10-20 or more years ago. I used to wonder why my COL with newer bullets is only 76mm while with older ones it's about 77mm. The bullets are equally deep in the case mouth and their ogives are the same but it's the very tip, how far it reaches, that causes the missing 1mm.
    Last edited by CH; 05-16-2017 at 01:47 PM.

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    CH you are welcome. Hope your 1000 pc box is exactly as you like. Please update me when you get yours.

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    Quote Originally Posted by CH View Post
    ...I used to wonder why my COL with newer bullets is only 76mm while with older ones it's about 77mm. The bullets are equally deep in the case mouth and their ogives are the same but it's the very tip, how far it reaches, that causes the missing 1mm.
    According to my copy of the Vihta Vuori reloading guide, COAL for the 185 gr FMJBT - D46 - is 76.8 mm. I thought this left too little bullet to case neck contact so I loaded the bullets a bit deeper. In My M28/76 with M28/30 barrel, these loads shot well, but I had sticky bolt with each round. The loads made with COAL according to the VV manual shot just as well, but no sticky bolt. BTW the VV manual, not surprisingly, lists Lapua as the case.

  10. #9
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    Here is the change of the D46 tip sharpness. On the right is the original factory competition load from the 1970s, widely used by both civilian and the SA match shooters. On the left is my own reload with new production D46.




  11. #10

    Default Changes in Lapua D166 and D46 bullet design

    I see what you mean.

    Here are 2 bullets, an old (from 70's or 80's I think) Lapua D47 and D46 produced last year. D47 on the left.



    Significant difference in length, but I don't see any big difference in the boat tail design (yet at least).



    D47 is the same bullet as D46, but with a cannelure.


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    Last edited by SPOV; 05-17-2017 at 10:26 PM.

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    Hi SPOV, thanks for the pictures. Yours show the difference very well.

    The boat tail, on the other hand, indeed seems unchanged which I consider a good thing.

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    It looks to me that the D47 bullet has a longer parallel portion of the bullet ending in a more abrupt taper to the tip. The taper of the D46 looks like it goes almost to the step. Optical illusion?
    Last edited by Buckstopper; 05-18-2017 at 04:30 PM. Reason: added text

  14. #13

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    Quote Originally Posted by Buckstopper View Post
    It looks to me that the D47 bullet has a longer parallel portion of the bullet ending in a more abrupt taper to the tip. The taper of the D46 looks like it goes almost to the step. Optical illusion?
    Yes, the shape is surprisingly different, I haven't noticed it before. What looks like a step is an optical illusion.


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