Hornady ELD-X Official Thread

[Edd]

I think there is more to it than pressure.

You can put palm pressure on the back of a car and push it across a parking lot. If you set the parking brake, it's going to take a lot more pressure to push it at the same speed.

I'm also not convinced you can make the blanket statement that a longer bearing surface will decrease velocity.

That's why I asked if anyone knew of any real data. I though Bryan Litz might have some. I'm guessing he reads discussions about bullets on this website.

 

[gohring3006]

I'd be willing to bet, once you find out your answer. We will be right.

 

[gohring3006]

It seems more surface area contacting the bore, more friction.
Which raises pressure so less powder is used. So more friction and less powder means slower velocity. At least this is how I figured it any way.[/QUOTE

Velocity is directly related to pressure.
So if the longer bearing surface does indeed raise pressure requiring less powder then Hornady just saved us powder on every shot to get the same performance in terms of velocity.

Not since you introduced more friction. 55,000psi with more friction will be slower than 55,000psi with less friction.

 

[Pdvdh]

I think there is more to it than pressure.

I'm also not convinced you can make the blanket statement that a longer bearing surface will decrease velocity.

I though Bryan Litz might have some. I'm guessing he reads discussions about bullets on this website.

Call Bryan and let us know what he says.

 

[Stumpm2]

There is a lot more to bearing surface/friction, pressure, and velocity. A longer bearing surface will create more friction and with fast burning powders will create a pressure spike early in the barrel and probably cause slower velocities. However, with slower powders, the longer bearing surface and friction may help to utilize all of the powder and keep a longer peak pressure down the barrel to create more velocity. If you can maintain peak pressure down more of the barrel, then 55,000 psi with more friction can be faster. It is all about the total area under the pressure curve which equates to the amount of potential energy available to be converted to heat and kinetic energy. Way too many variables including barrel twist, number of grooves, groove size, ect.

 

[Pdvdh]

Velocity is directly related to pressure.
So if the longer bearing surface does indeed raise pressure requiring less powder then Hornady just saved us powder on every shot to get the same performance in terms of velocity.

You've overlooked a detail or two. If all you want is an instantaneous pressure, use a faster burning powder with your long, heavy for caliber bullets - and end up with a lower MV. Higher MV is obtained by elevating pressure across the pressure curve. Through the peak, and the full length of the barrel.

HBN reduces friction between the bullet and the bore. This spreads out the peak pressure slightly, due to the lesser friction. Allows one to add a little more powder to regain the former peak pressure experienced with uncoated bullets. And the net result of the addition of powder is additional MV. Less friction, all other factors remaining the same except ability to add a tad bit more powder - more MV at equivalent peak pressure.

You can also drop down to a smaller capacity casing if you want to raise pressure with less powder. We all know how well that works, when higher MV is the desired goal.

 

[Pdvdh]

There is a lot more to bearing surface/friction, pressure, and velocity. A longer bearing surface will create more friction and with fast burning powders will create a pressure spike early in the barrel and probably cause slower velocities. However, with slower powders, the longer bearing surface and friction may help to utilize all of the powder and keep a longer peak pressure down the barrel to create more velocity. If you can maintain peak pressure down more of the barrel, then 55,000 psi with more friction can be faster. It is all about the total area under the pressure curve which equates to the amount of potential energy available to be converted to heat and kinetic energy. Way too many variables including barrel twist, number of grooves, groove size, ect.

This much is true. Lower bullet to bore friction will mean less of the energy/pressure the powder generates will be consumed/expended fighting friction/heat, and more will be available to increase MV.

Given equally well suited (ideal) powders for any two different bullets of the same weight, the bullet with less bore friction should always be able to be driven faster than the bullet creating more bore/bullet friction. This matter is well proven by shooters that HBN coat their bullets.

The only thing remaining unknown is the magnitude of the velocity loss that will result from the additional bullet/bore friction. It may not be a big deal or anything to fuss about. I provided the one relatively recent example of the 210 VLD versus the 215 Hybrid comparison because both of those bullets have been in heavy use now - the newer 215 Hybrid for several years, and the 210 VLD for many more years. The track record on MV is clear. The 215 Hybrid with its shorter bearing surface is consistently being driven to a higher muzzle velocity than the 210 VLD, even though it weighs 5gr more, and even with the use of the same/identical powder. Broz may be the member with the most first hand experience, since he's an avid user of both bullets and loads and shoots so much. He also gets feedback from others' rifles that he's involved with. Explanation = shorter bearing surface = less bullet to bore friction = higher MV.

Coat the bullets with HBN, reduce the friction a little more, and gain a little additional MV; all in the very same rifle. Which does away with almost all of the other possibilities that could be influencing/increasing MV.

 

[IdahoCTD]

Weight/mass is a factor along with bearing surface (friction). If the force applied (in this case the pressure they are loaded at with the same powder) is the same those two determine acceleration. ΣF = ma or all of the forces applied (including friction, gravity, pressure) equals mass times acceleration. We can measure acceleration as well to determine friction. If the 215 Berger is faster (acceleration) then the 210, loaded to equal pressure, then you can assume that less friction (shorter bearing surface) is a greater factor than the 5grs of additional weight (mass).

If you shot the original X bullets versus the TSX's, with the grooves cut in the bearing surface, this would make more sense. Since solid copper bullets are long for their weight they tend to have longer bearing surfaces which equals more drag. Grooving the exterior reduces the drag at the expense of BC. I'm not sure why they don't make the grooves look more like waves along the exterior instead of sharp edged grooves. That to me would reduce drag due to less sharp edges. It would be a rather simple process with a lathe turned bullet. The originals were pretty slow and fouled bad not to mention their on game performance wasn't very good due to the shallow and small hollow point.

 

[Edd]

I provided the one relatively recent example of the 210 VLD versus the 215 Hybrid comparison because both of those bullets have been in heavy use now - the newer 215 Hybrid for several years, and the 210 VLD for many more years. The track record on MV is clear. The 215 Hybrid with its shorter bearing surface is consistently being driven to a higher muzzle velocity than the 210 VLD, even though it weighs 5gr more, and even with the use of the same/identical powder.

You provided no data. Without data you are just guessing, we can all guess. Did you once guess that you could get more muzzle velocity with a slower twist?

 

[gohring3006]

You provided no data. Without data you are just guessing, we can all guess. Did you once guess that you could get more muzzle velocity with a slower twist?

Tell me what why the 215 Berger is faster than the 210 with the same charge weight. Tell us what other factor caused this besides bearing surface. Tell me why everyone is wrong about this. Please

 

[Edd]

I didn't say everyone is wrong, I asked if there was any data to support longer bearing surface equals less velocity. Do you have any?

 

[Pdvdh]

You provided no data. Without data you are just guessing, we can all guess. Did you once guess that you could get more muzzle velocity with a slower twist?

I've got this figured out. Your prodding isn't compelling me to produce any more explanation/data than I already have. Folks consistently getting additional MV from the same rifle with the 215 Hybrid versus the 210 VLD, that doesn't constitute data?

You're the one that desires data that measures up to your standards. Which is why I suggested you call Bryan or someone else measuring up to your data standards. Then share with the rest of us.

 

[gohring3006]

Yes I do....
The 215 Berger Hybris is faster than the 210 VLD.
Reason....
The 215 Berger has a shorter bearing surface.
Data.... Every thread ever started and ended on this very subject.

 

[waveslayer]

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