Hornady ELD-X bullets

[AaronSkipDavidson]

The big problem with the currently measured data for polymer tips relates to the testing criteria. If that test was done at typical 308 velocities, the initial velocities may have been too low to cause the tip problems. Early test data with the 7mm 175 gr Nosler LRAB showed a BC of 0.600 with 7 STW muzzle velocities, and near advertised BCs (0.674) when launched at 2400 fps MV in a special twist gun.

From what I understand the tip issue only starts to be relevant when initial velocities are 2700 fps and above. Testing on tipped bullets at much lower velocities should not show the melting tip data.

I've attached a pic of a bullet just out of the muzzle. Initial velocity was 2800 fps, and the bullet is a FMJ. Check out the tip temp! Remember that copper is an excellent conductor and the bullet acts as a big heat sink, whereas tips are plastic which is a great insulator. From the testing and radar generated drag data it appears that the tips shed in layers! Very cool stuff.

 

[AaronSkipDavidson]

I think Aaron summed it up well. I too have been left wanting more. That is, a high BC offering with predictable expansion. Since I primarily use a 308 win, reliable expansion at lower than average velocities is very important to me and increases the effective range of the 308 dramatically. The ABLR was supposed to fill this niche but they seem to be very difficult to tune in many rifles. I have one that shoots them well but struggle to find others to shoot them well.

I've been a fan of Hornaday since I started long range shooting in the early 90s. They're a very accurate and consistent bullet with great terminal performance. The downside has been lower BCs for most of their bullets. The 6.4 140, 7mm 162 and 208 AMAXs were the best which isn't much of a selection.

On that note, I have found that the BCs of the 168 and 178 AMAXs have fallen off the table by the time they reach 1000 yards. Hopefully the new designs improve that.

Aaron, is the 178 ELDX formed any differently than the 178 AMAX?

The 178 ELD-X uses the same boat tail and ogive as the Hornady HPBT. The jacket is much different than the Amax, and the length will be longer than the Amax.

 

[rooster721]

The big problem with the currently measured data for polymer tips relates to the testing criteria. If that test was done at typical 308 velocities, the initial velocities may have been too low to cause the tip problems. Early test data with the 7mm 175 gr Nosler LRAB showed a BC of 0.600 with 7 STW muzzle velocities, and near advertised BCs (0.674) when launched at 2400 fps MV in a special twist gun.

From what I understand the tip issue only starts to be relevant when initial velocities are 2700 fps and above. Testing on tipped bullets at much lower velocities should not show the melting tip data.

I've attached a pic of a bullet just out of the muzzle. Initial velocity was 2800 fps, and the bullet is a FMJ. Check out the tip temp! Remember that copper is an excellent conductor and the bullet acts as a big heat sink, whereas tips are plastic which is a great insulator. From the testing and radar generated drag data it appears that the tips shed in layers! Very cool stuff.

That's a very interesting picture... personally, and for years, I've wondered whether excessive heat on j-4 jacketed bullets in (my) Lazzeroni Firebird was the answer to all the problems I've had with every j-4 bullet I tried to load. Berger Hunting, Berger Target, Marshall's Matrix 190's, even to certain degrees (no pun intended) with sierra jacketed bullets-- every type mentioned had 'some' that would blow up like puffs of smoke before 100 yard paper... betcha any money (now/looking at that pic) that it's all been due to excessive heat on them over & above anything else.. that led to jacket failure*

Thanks for posting that.

Because of the mentioned circumstance, I am absolutely as anxious as yourself about a bullet design like this with "heat" effects in consideration to design! Albiet being the tip, it still is very relevant! Excellent to now have a better-BC bullet to soon use than the LRX I've made my #1 pick for so long. I can hardly wait to find these in-store.

In your guys testing (Aaron) What barrel twist did you use in the LRM's, or STW's that you shot the 175's through? I haven't seen a bullet length noted anyplace to try use as an idea thru the twist rate calculators, regarding stabilities & barrel twists n so on.. wonder if you could shed some light on that for us?

 

[AaronSkipDavidson]

Radar Data was collected with the following:

6.5mm from a 1:8
7mm from a 1:8.75 (also shot well in 1:9.25)
30 Cal from a 1:10

 

[Scot E]

Saw this posted on another thread.

Caliber, Weight, Bearing Surface, Minimum Twist

6.5 – 143, .555", 1-8.5"
7 mm – 162, .533", 1-9.5"
7 mm – 175, .570", 1-8.75"
30 – 200, .630", 1-10"
30 – 212, .626", 1-10"
30 – 220, .730", 1-10"

 

[drpbroun5]

Has anyone on the forum seen or better yet shot these bullets? If so what are your thoughts? How did they fly? How have they performed on game? I have seen what the Gunwerks folks have said, but has anyone else gotten them? Thanks.
Paul

 

[KYpatriot]

Well, I dont see what all the speculation is about with respect to tip melting, if it exists. I suspect it isnt much of a problem, or we would have noticed before now. 10% BC reductions would have been noticed most likely if they were actually there.

The fact is, we dont have to guess at all. We have wind tunnels to answer these kind of questions, that will flow faster than any bullet fired from a hand held rifle.

Put A polymer tip bullet in a wind tunnel, run it at Mach 3, (roughly 3400fps) and let a high speed camera tell us the rest. Measure how many milliseconds it takes the tip to degrade. Directly measure the drag. We have the ability to KNOW, definitively, we dont have to guess.

 

[Rich Coyle]

Didn't Hornady get the same type of information with the dopplar radar?

 

[Capt RB]

Well, I dont see what all the speculation is about with respect to tip melting, if it exists. I suspect it isnt much of a problem, or we would have noticed before now. 10% BC reductions would have been noticed most likely if they were actually there.

The fact is, we dont have to guess at all. We have wind tunnels to answer these kind of questions, that will flow faster than any bullet fired from a hand held rifle.

Put A polymer tip bullet in a wind tunnel, run it at Mach 3, (roughly 3400fps) and let a high speed camera tell us the rest. Measure how many milliseconds it takes the tip to degrade. Directly measure the drag. We have the ability to KNOW, definitively, we dont have to guess.

You would need more than just the airflow friction. The heat from the expanding gases from the powder charge is the primary source. Look at the thermal image Aaron provided on the previous page. The amount of surface area a boattail provides plus being of a highly conductive material cannot be heated that way from the tip's cross section friction alone

 

[KYpatriot]

Yes sir I understand the picture, it is depicting heat on the base from the expanding gases and frictional heating on the bearing surface. But what we are talking about here is Hornady is claiming that aerodynamic heating is causing the tips to melt away or get soft and slump, causing increased drag. There isnt time for heat in the jacket to conduct to the tip, so any damage to the tip must be caused by aerodynamc heating alone I would think.

In other words, the jacket is being heated by barrel friction, and the tip by aerodynamic friction.

 

[KYpatriot]

Didn't Hornady get the same type of information with the dopplar radar?

No. Im talking about mounting the bullet in the test fixture in the wind tunnel, run it up to 3000 fps or so, and then simply look at the tip. You could also directly measure the drag on the bullet. The bullet wouldnt be rotating, but you could at least see aerodynamic heating.

Or you could wait for a no-wind day, shoot it straight up, and catch it when it falls down and see if the tip melted off. Any volunteers??

 

[BadDogPSD]

Perhaps a solution in search of a problem? Wouldn't be the first time!

 

[gunner69]

Bottom line for me is, if it flies more predictably and kills better, I'm in!

Called Hornady. They will actually not be shipping the ELD-X till February. Seems like they prematurely announced! Guess they were taking a page from the Apple iPhone marketing folks.......

I ordered the 175's for my 7LRM (Gunwerks LR1000). Aaron love some load data! And some the 163's (or 165's can't remember) for my 284 Shehane.

 

[brentc]

I'll have some 30 cal 200s in a couple days. Don't know what this February thing is about.