108 ELD vs 105 Amax

Discussion in '6mm, 6.5mm, and .25 Cal (Not 6BR)' started by 46and2, Sep 15, 2019.

  1. 46and2

    46and2

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    Not sure where to post this but... can anyone tell me if the ogive is the same or different for these two bullets????
    If anyone can post pics of these two side by side that would be awesome.

    Thanks.
     
  2. SSL

    SSL Gold $$ Contributor

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    Hornady rep told me that all Amax and Eld-M bullets are identical in every way except the material used for the tips. Eld-M bullets supposedly have tougher tips for less heat erosion in flight. Only Amax/Eld-M bullets I use are .224", 52-grain and I can see no difference in shape or performance.
     
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  3. 46and2

    46and2

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    Thanks,
    I have a new AR10 6cm barrel and it will not feed 105 Hybrids, VLD or RDF bullets without malfunctions. Its not a magazine issue, the meplat hits the barrel extension face causing failure to feed.

    Only the tangent ogive or shorter nose bullets will chamber reliably.
    Thanks again. I just shot Hornady an email too.
     
    Last edited: Sep 15, 2019
  4. Raptor

    Raptor

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    SSL is correct. I was told the same thing. I shoot them out of my 284 and have found that they do fly a little flatter out past 700yds. I shoot them in my 6.5 but the 284 is the only one I have really good long range data on. My son in laws also shoot them and they have found the same thing with theirs.....
     
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  5. 46and2

    46and2

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    I wonder where the extra 3 gr came from??
    More boat tail or shank, i really don't believe the new tip weighs that much more.
     
  6. Raptor

    Raptor

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    What kind of AR10 do you have and what barrel are you using???
     
  7. 46and2

    46and2

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    Dpms upper, Mcgowen barrel.
     
  8. 284winner

    284winner Gold $$ Contributor

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    I was told the same however the 108 and 105 will more than likely have a different measurement.
     
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  9. SSL

    SSL Gold $$ Contributor

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    Yep...senior moment. Totally missed the difference in weight. My remark should be limited to AMax/ELD-M bullets of identical weight. Good catch.
     
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  10. 46and2

    46and2

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    Wonder where the extra 3gr is, longer shank???

    I can't see the new tip weighing 3gr more.
     
    Last edited: Sep 20, 2019
  11. dmoran

    dmoran Donovan Moran Silver $$ Contributor

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    Below is a blown-up image of a 105 AMax and a 108 ELD-M.
    Besides the weight indifference, some of the other specifications are also different (at least on these of mine):

    AMax-ELDM.png
     
  12. fyrewall

    fyrewall

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    I have noticed differences between the .224 75 Amax and the .224 75 ELDM. I needed to seat the .224 ELDM bullet deeper, it has a longer bearing area. This also appears to be true with the .243 105 Amax & .243 108 ELDM. I found the .224, & .243 and lighter weight .264 Amax bullets to be good varmint bullets. I was sort of unhappy to see a big price increase. The extra 3 grains sure appears to be from a longer bearing area - jacket & core.
     
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  13. 46and2

    46and2

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    Thanks.
     
  14. Laurie

    Laurie

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    As Donovan says, they're not the same, tip material and 3gn aside, at least according to Bryan Litz and his various books of words (or more precisely his scale drawings and measurements) on bullet design and performance.

    The 108 ELD is slightly longer overall than the AMax according to Mr Litz's measurements, has a longer tail section, and a slightly shorter bearing surface length / shank. The ELD nose length is a little longer, but the radius values are pretty close.

    A 3gn weight change, less than 3%, doesn't necessarily need or imply a longer bullet - it can come from a small increase or decrease in the lead core's length or that of the jacket employed.

    The relevant bits are:

    Tail section: both 8-deg angle, but the ELD 0.164" v AMax 0.135"

    Shank: ELD comes out at 0.397" length v AMax 0.429"

    Nose: ELD measures 0.691" and AMax 0.658 (that may be down to tip shape changes rather than profile)

    Nose radius: ELD 9.60 calibres v AMax 10.09 calibres

    Rt/R value: ELD 0.91 v AMax 0.88 (ie both models much closer to tangent ogive form than secant / VLD)

    Form factor: ELD is 0.975 v AMax 1.010 (ie the ELD generates 2.5% less drag than the G7 reference projectile and the AMax 1% more)

    G7 BC value: ELD 0.268 and AMax 0.252 mostly coming from the form factor reduction rather than the extra 3gn weight.


    Given the difficulty in measuring some parts of bullets and that Bryan has changed his measurement methodology between his early work on bullet design including the Amax and his recent investigations, small changes are best ignored, especially as there may be say 10 thou' variances between production lots, but the tail and shank changes are probably large enough to say 'modest redesign' rather than production or measurement induced factors.

    I'd been intrigued by some of the high G7 BC values claimed by Hornady for the ELD bullets (in all calibres not just 243). So when I received my copy of the third edition of Bryan Litz's Ballistic Performance of Rifle Bullets, one of the first things I checked out was whether Hornady's claims are accurate - they are - and also whether the ELDs were AMax shape designs with a new tougher tip or something more. Where a comparison can be done (some can't) it seems that a few ELDs are the same shape as their predecessors, but some have seen a considerable redesign. The 243 123gn ELD is a very different design from the the same weight AMax for example, so any COAL measurements based on where the AMax touches the lands will be well out for the ELD.

    Intriguingly, one or two ELDs (the 162gn 284 version stands out here) have a noticeably better form factor hence BC despite very small shape changes. That suggests Hornady's AMax melting-in-flight plastic tip claim is valid despite many people on forums rubbishing it as marketing hype.

    The same / different 'form' issue also applies to members of Sierra's HPBT MatchKing range. Some models are no different to the SMKs of yesteryear, pointed meplats aside, whilst others have seen a major redesign. For instance, anybody who loads 123gn 0.264 MatchKings will see a large difference between the 'new' pointed version and what they had in the past so 'historic' COAL settings will be very wrong. Mixing 'old' and 'new' wouldn't be a good idea either even if their loads and seating depths still work given some significant BC differences.
     
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  15. RussellJ

    RussellJ Silver $$ Contributor

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    upload_2019-9-20_17-49-17.png upload_2019-9-20_17-50-9.png
     
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  16. 46and2

    46and2

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    So.... looks like it will be a lot longer before I'll need to run the 108 after all. I just found a guy selling 1200 of these 105s. Thanks everyone for the advice.
     
  17. 46and2

    46and2

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  18. fyrewall

    fyrewall

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    Here is a photo of the .264 123 Amax & .264 123 ELDM

    Now that the 123 .264 Amax is extinct I shoot 123 .264 ELDM's out of my 6.5-06 at rodents and steel targets. I like the extra speed of the 120 & 123 over 140's and am willing to trade off wind advantages for slighter flatter trajectory and better splat effect.. The bearing surface or shank on the ELDM appears to be longer and seating depths needed to be adjusted. Hard to say from this photo but the Amax & its jacket appears to be slightly longer. Boat tails appear to be very similar.

    The much smaller .224 75 ELDM @ 3300 keeps up with the .264 123 ELDM @ 3150 at least to 500 yards in my limited comparison. The .22-.250 loads use 17 grains less powder & bullets cost about $12 less than the 6.5mm's making the .22-.250 more cost effective. Barrel life is about the same, the .22-.250 might be slightly better.

    P9200038.JPG
     

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