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Hornaday eld match bullets

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Does anybody know if Brian litz has measured the bc on these hornaday bullets yet as the 7mm 180gr eldm have a huge bc.way higher than any other in the same calibre/weight.

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162gn   G1: 0.639, G7: 0.327; G7 form factor: 0.877; min twist 10.4 / optimal twist 9.3 or faster

180gn   G1: 0.703, G7: 0.360; G7 form factor: 0.886; min twist 9.8 / optimal twist 8.8 or faster

 

The 162 is not the old AMax with a heat resistant tip. It is a relatively mild but apparently effective redesign with a longer / larger radius nose and Rt/R ratio of 0.50 showing it has a very aggressive secant ogive form, ie is a true VLD type now. The ELD's G7 BC has risen from the AMax''s 0.307.

The 180's BC isn't that much greater than that of the 180gn Berger VLD and Hybrid (0.348/0.345) which with pointing will slightly exceed the ELD value.

Other contenders are Sierra 180 (0.337) and the new factory pointed 183 MK at 0.377 (in stock at Henry Krank, and a really superb 7mm so far as consistency goes but needs an 8.5" or faster twist). With an 0.859 form factor, the 183 SMK is the most aerodynamically efficient of the bunch

Then there is the 180gn Lapua Scenar L at a 'mere' 0.319 G7 but which is a superb long-range performer in a barrel that likes it. Paul Hill used the much undervalued Lapua in the relatively unpopular 7 SAUM cartridge  in the European F-Class championships in September at Bisley and walked away with almost every F-Open medal going with an aggregate score of 491.57v for the six matches out of a possible 500.100v Think about that! That's 91 ex 100 shots (30 each at 800 and 900; 40 at 1,000) in a 10.6" 5-ring and 57 of them in the 5.3" V-ring!

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Thanks Laurie.

I remember you were a little sceptical on the 180gr eldm having a higher BC than the bergers when I asked you via a pm.though minimal they are actually a fraction better then. My main thought was in them being much cheaper than the bergers.I recently shot the 180gr scenar L's in my 284 again 2 weeks ago and they did shoot quite stunningly.my 7mm saum has been rebarrel this week by Neil Mckillop with an f class size barrel and his reamer suits the 180gr hybrids and the 162gr amaxs perfectly but the scenars seat deeper.I am looking forward to shooting it .somehow I knew you would know.

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21 - 8 on Friday's 1K stage and 13 on the following day's.

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Yes, but not by as much as was previously believed and disseminated in Litz's  early editions of Applied  Ballistics for Long Range Shooting where a range of potential improvement of 3 to 7% was quoted. (Degree of meplat diameter reduction allied to calibre with small calibres gaining the most.)

Bryan Litz's book Ballistic Performance of Rifle Bullets has just been republished in its much expanded 3rd edition (around 950 bullet models now covered in all calibres from .17 to .510" bar 7.7mm (.303) and 8mm), and interestingly it has some models in their old unpointed form retested in new and shiny 'pointed' versions side by side.

This has turned out to be interesting in two unrelated ways. First, you cannot always do a simple side by side comparison for Sierra MatchKings for pointing alone. It becomes apparent when you look at the bullet drawings and dimensions that Sierra has taken the opportunity to indulge in some basic redesign work while at it, so there is more to what causes measurement changes than 'pointing 'alone. (The same applies to the Sierra TMKs in some cases. Some such as the 168 and 175gn .308 TMKs are completely new designs and will behave very differently in the chamber / barrel as well as in their external ballistics to their still available blunt tangent ogive SMK predecessors. Some such as the 6mm 95gn SMK and TMK share an identical form bar the tip.)

So one has to find examples where  the basics are unchanged leaving just  pointing. One such is the 0.224" 90gn SMK where the original's 0.062" dia. meplat has been reduced to a most impressive 0.045". (Few home 'pointers' can get down to that size.) The drag related G7 Form Factor has reduced from 0.999 to 0.991 which in turn increases the average G7 BC from 0.257 to 0.259, an increase that's not going to be noticeable on the range. Bearing in mind that Litz says there is a one or two percent error tolerance in his methodology, that could mean that in real life there might be a small BC increase to a nil increase or even a reduction depending on which way the parameters worked here.

Litz looks at bullet tip trimming and pointing both separately and in concert as a section in Modern Advancements in Long Range Shooting Vol. II and BC benefits range from nil to at most 3% in BC terms IIRC, although there may be benefits in reducing BC variations between individual bullets giving better elevation consistency at long ranges.

As I said, the other interesting feature to come out is that of a bit of quiet redesign of some models. The antediluvian 0.224" 80gn SMK in its new 'pointed' form is not otherwise identical to its older unpointed cousin. About the only things that remains the same are bullet OAL and the 9-deg tail angle, with minor but useful changes / improvements to shank length and nose shape it having a slightly longer radius 'pointier' front end so its form factor reduces from 1.030 to 0.968 and BC increases from 0.221 to 0.235, a useful 6+%  improvement. This is achieved at the expense of a 'sharper' transition from parallel shank to nose sections changing it from a true tangent design to one that will be a bit fussier re its position to the lands. So, if you take the new model and simply load it as per the older version, the results will likely change and more likely for the worse at that.

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