123gr ELD Match BC Discrepancy

[NugginFutz]

Not sure if this will help for real world results vs stated info, but I would use the lower stated BC and here's why.....

I recall others a few years back saying AMAX needed to use lower BC for drop calc so I used that for the base BC which was said to use 0.42.

The trajectory didn't line up and I did do proper scope center to bore measurement. There could have been an error on my part somewhere, but I didn't look into it and just used the real world results as calc values to me are a starting point to get close and then map actual real world data, re-plot from there.

22" barrel. AMAX chrono'd pretty close around 2510 fps and my origial cal value I put 2500 before I had chrono data. 100 yd zero.

300 yds called for 4.82 MOA, I was 7 MOA. 500 yds called for 12.73 MOA (mine is 1/4 MOA increments) and 12.75 did perfect. This was the furthest I used AMAX for, I don't recall if 750 yds or not so I'll just say not.

Finally ran out of my AMAX stockpile and used the ELD last week or week before and don't recall that fps off the top of my head, but I think the ones tested from this batch was a tad faster than AMAX. (all factory loads here)

I have new actual values written down and I'd have to dig. But I recall 500 yds changed to 15 MOA. 750 yds my old calc for AMAX stated 26 MOA, but I dialed to 29.75 MOA and lucky chance that was the required adjustment. 29/30 hits on the gong. I thought I would try to dial in better by 1/4 MOA about 3 rds in and that was the miss, went back to 29.75 and kept banging.

The discrepancy with the Amax bullets (and apparently with several other poly-tipped bullets, such as the Nosler) was due to a phenomena known as aero-heating. Friction at high velocities caused the plastic tips to melt, resulting in a decaying BC as the drag increased with the melting tips.

The ELD tips eliminated that issue. Further, where the BC's were previously calculated, Hornady now publishes their BC's resulting from direct measurements using their doppler radar system.

In other words, newbie, the data on the new ELD boxes is quite accurate.

[newb]

The discrepancy with the Amax bullets (and apparently with several other poly-tipped bullets, such as the Nosler) was due to a phenomena known as aero-heating. Friction at high velocities caused the plastic tips to melt, resulting in a decaying BC as the drag increased with the melting tips.

The ELD tips eliminated that issue. Further, where the BC's were previously calculated, Hornady now publishes their BC's resulting from direct measurements using their doppler radar system.

In other words, newbie, the data on the new ELD boxes is quite accurate.

If one watches their sales pitch video for their new A-TIP they talk about this bullet supposed to greatly reduce the BC variations found in standard production bullets. Which I believe would mean the likes of ELD, etc have noted BC variations +/- advertised value.

If I recall correctly reading various places the AMAX tip softening with some deformation didn't happen until at least 600 yds and with velocities higher than Grendel at that distance. Some long range guys claiming they didn't notice anything at 1,000 yds. But none the less that is a dead horse.

I dug up my values and 10 ft chrono data agrees right in there with the ELD velocity stated on box, at least with the rounds I ran chrono on. According to the trajectory simulator ran just now, with that Hornady stated G1 BC and my altitude etc correction, MOA drop at 500 yds should be 9.65. My actual drop was 15 MOA. I don't have doppler radar to track down range. The best I can do is state the data I personally collected.

The only thing left I could re-verify on my end to rule out would be 100 yd scope box test.

[NugginFutz]

newb - I can't speak to your experience, but let me share mine.

Last weekend I took my 22" Bull Barrelled BHW out for a romp. I sent some rounds down range, using the ballistic computer's wind and elevation calls for dialup and wind holds. I was meticulous about the data I entered, regarding measured wind, temperature and elevation. MV was 2570, from the most recent outing's chronograph readings. I entered the .506 G1 BC for my 123 ELD's, as indicated by the box, the Hornady website, and the the ballistic calculator's internal library.

I checked zero @ 100, and dialed up in the calculated elevations at various distances and was able to put first round hits on almost every target. Other than changes to my wind holds, I did not deviate from the drop chart generated by my app.

These are some the hits on steel out to 1000 yards.

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My come ups were 2.0 mils @ 400 yards, 6.6 mils @ 800 yards, and 9.5 mils @ 1000 yards. Wind was 15 mph L-R, gusting to 25. This particular range is @ 6600 ft ASL.

A quick check for a 500 yard drop in MOA shows I would have used a 10.4 MOA come up, somewhat more than your calculated hold of 9.7, but reasonably close.

What I'm trying to illustrate is that IF your data is good, a quality calculator can put you on target with a fair measure of accuracy. Mind that fact that it is a model of a real world situation, and the deviations from the real world come from primarily from data entry errors.

So, if you are getting a 15 moa drop at 500 yards, and assuming that your 2510 MV is accurate, I would have to come to one of two possible conclusions: 1) we are shooting two different bullets, or 2) we are measuring our drops differently (scope error).

While #1 is possible, it is unlikely that the boxes are mismarked. The would leave me suspecting an issue with the scope. I have checked my scope, using a technique described by Bryan Litz, called the Tall Target Test. This, combined with the well known Box Test, has given me confidence in the scope mounted on this particular rifle.

As I said, I can't speak to your situation, directly, newb, but my experience tends to align with the stated BC of the round in question. So there you have it - we have two disjointed experiences.