Pressure Differences - ELD-M and ELD-X

Hey team,

Has anyone noticed significant pressure differences between the ELD-M and ELD-X of the same weight?

I've done some load development with the 162g ELD-M for my 7mm Rem Mag but have been given some 162g ELD-X to try out. So I'm wondering if it is safe to start roughly where I was with the ELD-M, or whether I need to start from scratch?

Book data is the same for both pills and the ever dangerous internet searching suggests most people are finding good results with both pills at 70 - 72g AR2217.

My accurate load with the ELD-M was 70.5g AR2217 with zero pressure signs (only went up to 71g because of availability at the time), so was thinking about starting at 70g and working up to 72g.

All suggestions welcome.

Cheers,
Elliott

I use x and m in my 6.5 same powder weights no pressure signs.

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Originally Posted by 25 /08 IMP

I use x and m in my 6.5 same powder weights no pressure signs.

Sent from my CPH1903 using Tapatalk

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Thanks mate. Are they warm loads?

From what I have heard the m is softer than the x, so I would expect higher pressure with the x at the same powder charge, but I have no idea whether it’s enough to be an issue.
I would play it safe and start a bit lower and work up (which is recommended practice even when changing lot numbers of the same projectile - not that I do that myself).

ELD-X jackets are harder, which can push pressure up as they engrave onto the lands. It might be fine, but I would start a grain or two lower just in case.

The X hit pressure 1 -1.5gr earlier in my 284 over the M. Both 162gr

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Originally Posted by stagstalker

The X hit pressure 1 -1.5gr earlier in my 284 over the M. Both 162gr

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Awesome, that's great info thanks mate.

Cheers for all the other info too - will be load from 1.5g lower than the ELD-M load, which doesn't show pressure signs.

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Originally Posted by Edunn

Thanks mate. Are they warm loads?

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They are near max loads


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The eldx has a void behind the polymer tip, making it substantially (relatively speaking at least) longer than the eldm, hence the slightly higher BC with the eldx. You will need to adjust your seating die otherwise you will reduce the internal volume of the case under the bullet and increase the pressure.

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Originally Posted by bang

The eldx has a void behind the polymer tip, making it substantially (relatively speaking at least) longer than the eldm, hence the slightly higher BC with the eldx. You will need to adjust your seating die otherwise you will reduce the internal volume of the case under the bullet and increase the pressure.

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Where did you get that info? Just doing a comparison the 7mm 162eldx has a bc of 0.630 and the 162eldm has a bc of 0.670

huh, yea you are right. Comparing 30 cal 178grain (the ones I have been using), BC is .547 for eldm vs .552 for eldx. The eldx is noticably longer when comparing side by side. are the 7mm ones not?

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Originally Posted by bang

huh, yea you are right. Comparing 30 cal 178grain (the ones I have been using), BC is .547 for eldm vs .552 for eldx. The eldx is noticably longer when comparing side by side. are the 7mm ones not?

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Strange, 7mm 162gr X is noticeably larger then the M like you say but the BC of the 7mm M is definitely recorded as being higher.

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Originally Posted by bang

huh, yea you are right. Comparing 30 cal 178grain (the ones I have been using), BC is .547 for eldm vs .552 for eldx. The eldx is noticably longer when comparing side by side. are the 7mm ones not?

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Have not got my hot little hands on them yet. However the book data suggests the same COAL. Of course I'll do some dodgy measurements when I do receive them and try to figure out an appropriate seating depth myself.

Wasn't planning on trying everything exactly the same as the ELD-M - was merely looking for a powder starting point, given my rifle seems to handle above book max charges with the ELD-M perfectly fine.

I'd say the plan will be to start 1.5g lower than where I ended up with the ELD-M (which was below any sign of pressure).

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Originally Posted by 25 /08 IMP

I use x and m in my 6.5 same powder weights no pressure signs.

Sent from my CPH1903 using Tapatalk

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I've found the same even though the ELD-X is 3gr heavier. Exact pressure difference would no doubt be different.

The 30cal eldx 178 are quite a bit bigger than the 178eldms so can see why the eldx has a better bc even though it is negligible

I have played around with both in 162gr and the ELD-X is a longer bullet which will reduce useable case capacity(increasing pressure) when seated at the same length.
The ELD-X also has a shorter Ogive and will contact the lands around 20thou earlier so duplicating a ELD-M load OAL could also run into pressure issues there.

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Originally Posted by Cooper

I have played around with both in 162gr and the ELD-X is a longer bullet which will reduce useable case capacity(increasing pressure) when seated at the same length.
The ELD-X also has a shorter Ogive and will contact the lands around 20thou earlier so duplicating a ELD-M load OAL could also run into pressure issues there.

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Thanks mate! Great info!

I know it's a pain, but I would start from scratch. They are different bullets after all.

I've shot both in my rem mag, started with the ELD-M and now use the ELDX. The powder charge for the ELD-M was quite a bit higher than the ELDX from memory, they were very compressed at length but with the ELDX I've got powder moving when I shake the rounds at the same coal.

Hope that helps.

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Originally Posted by Rated M for Magnum

I know it's a pain, but I would start from scratch. They are different bullets after all.

I've shot both in my rem mag, started with the ELD-M and now use the ELDX. The powder charge for the ELD-M was quite a bit higher than the ELDX from memory, they were very compressed at length but with the ELDX I've got powder moving when I shake the rounds at the same coal.

Hope that helps.

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Yep, I'm reasonably confident starting 1.5g below should be all good, but just in case I will load up one round from start to where I expect finish to be and check for pressure signs. Will use that as my cut off for when I test groupings.

Just out of curiosity does hornady have different min/max charge recommendations for the ELD-X vs ELD-M? Or do they lump them all together? I dont have the hornady manual.

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Originally Posted by Hunty1

Just out of curiosity does hornady have different min/max charge recommendations for the ELD-X vs ELD-M? Or do they lump them all together? I dont have the hornady manual.

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Nah, Hornady lump all weights by Cartridge. The 162gr weight class is at a max of 68.5gr of H1000

Attachment 138503

Here they are side by side, 162 ELD-M ON the left, 162 ELD-X in the middle and 175 ELD-X on the right.

How did you get on @Edunn? Have you managed to get out and shoot them yet?

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Originally Posted by Rated M for Magnum

Attachment 138503

Here they are side by side, 162 ELD-M ON the left, 162 ELD-X in the middle and 175 ELD-X on the right.

How did you get on @Edunn? Have you managed to get out and shoot them yet?

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Topical prompt!

Had quite an interesting experience over the weekend. On Saturday morning I loaded up one round each of the 162g ELDX from 68.5g up to 74.0g (AR2217) - obviously expecting to have to stop shooting around the 72.0g mark. COAL was 3.400", which comfortably fits in my mag (Browning X Bolt) and is 0.020" off lands.

Had faint ejector marks and flat-ish primers from 72.5 through to 74.0, but they all shot fine with no major concerns at the time. Chrono read 3115 for the 74.0g charge.

Thought I was onto a winner here, so loaded up four each of 72.5, 73.0, 73.5, and 74.0.

72.5g shot a 1" group but nothing to be excited about. Faint ejector stamp, relatively flat primer. Waited for everything to cool down, then loaded up 73.0g. First shot, noticeably more felt recoil, and bolt very sticky with a crater-like ejector stamp. Chrono showed 3144 fps. I thought it must have been a rogue load (given the day before was fine), so tried one more with exactly the same result. The tough pill to swallow is both rounds went through the same hole but far too much pressure to use that load safely.

I didn't shoot any more (obviously) and went on to validate my 7mm08 bushpig out to 300, which went really well and saved the day.

Did a lot of thinking about why the difference between the two days last night have come to the conclusion that:

1) Charges were accurate, as I weighed the leftover rounds
2) Sunday was slightly warmer and sunnier than Saturday. But realistically, I'm in Dunedin, so was only a one/two degree difference.
3) I should have paid more attention to the velocities the day before - on review, there was a flat-ish velocity node from 70.5 through to 72.0, then a jump of 97fps from 72.0 to 72.5. Probably indicating that I was hitting pressure around that 72g mark even though there were only very light symptoms. I guess this means that any small changes in conditions could cause a pressure spike? That segues on to my final finding:
4) For some outrageous and unknown reason, I had loaded everything at 3.400" COAL on Saturday and 3.990" on Sunday. I only clicked to that last night when I was re-weighing and re-measuring everything - moral of that story, is have everything written down right in front of me all the time - I follow recipes for a living (scientist) so should have bloody known better than to do it off the top of my head.

So the plan, now, is to load up four of each from 70.5 through to 72.0 in half grain increments and try again.

Very happy to hear everyone's thoughts, laughs, tut-tut-tutting, and somewhat solicited advice.

Cheers,
Elliott

Currently going through the same thing with trying to find accurate loads for a different bullet in my 7mm Mag and know how easy it is to get caught up in the hunt for speed.

I would back it down to around 70.5gr Maybe up to 72 if it flattens out? and look for something that shoots good around 2960fps

Is 3.990" coal a typo?

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Originally Posted by Cooper

Currently going through the same thing with trying to find accurate loads for a different bullet in my 7mm Mag and know how easy it is to get caught up in the hunt for speed.

I would back it down to around 70.5gr Maybe up to 72 if it flattens out? and look for something that shoots good around 2960fps

Is 3.990" coal a typo?

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Bugger! 3.990" is very much a typo haha. Can't figure out how to edit the post but meant to say 3.390" so 0.010" shorter than the first day pressure test.

Yep that's the plan exactly mate - Pretty confident there will be something in that group of interest. In the pressure test there was only just over an inch variation from 68.5g through to 72.0g.