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180 ELD-M Instability?

04 Aug 2018
@ 12:26 pm (GMT)

Jim Moseley

My hunting buddy and I have been testing the Hornady 180 gr eld match. We are both shooting the 7 mag and get unusual results that I have no answer to. One day we are shooting outstanding groups only to follow up several days later with groups that look like a scattergun. Both rifles are 8 twist with MV's of 2990 and 3010. He's using H-1000 and I'm loading RL26. As anyone else had inconsistencies with the 180's?

Thanks,

Jim

Replies

06 Aug 2018
@ 08:38 am (GMT)

Nathan Foster

Re: 180 ELD-M Instability?
Hi Jim, yes, this is a problem with 8 twists. When Hornady and others do their calcs, it is normally around the likes of a 7mm-08 or .284 - match test guns. Hence why we end up with twist rate recommendations on the ammo boxes or via some whizz bang computer program. But in a magnum, the extra speed produces more RPM. Your rifle has been particularly fast Jim, its up with the Practical (not a great sign of bore dimensions). It may also be affected by the conditions of the bore on the day relative to your cleaning regimes and perhaps also ambient temperatures. A higher level of copper fouling will aid stability, low copper and high carbon will decrease stability (note I have made an assumption about the bore finish). From memory, you have a copy of my accurizing book. When you get time, go to the section which talks about bore finish versus dimensions versus twist.

Since 2011 I have been warning against the 8 twist 7mm but I am just one voice versus many who disagree and make a lot of noise doing it. So I guess I'll just keep shooting my accurate rifles while they can carry on shooting their inaccurate rifles and making up bullshit stories about bullets changing directions before they go to sleep.

In your case Jim, you could try to look for a sweet spot at around 2860fps. But if the rifle does not like this and only likes hot loads, what you may find is that the barrel just keeps getting worse and yes, you could for example make a 195gr work, but you might not like this bullet for hunting lean White Tail out long (zero expansion). What I am trying to say here, is that you need to discern when to call it quits- before you have spent the equivalent of a new barrel on powder and projectiles. A lot of guys just don't know when to give up. Yours will be confusing you because it will have shot quite well when the throat was new and rough but as the bore smoothed out, it has started to produce problems.

If you want to, try the 175gr ELD-X, work up loads from down low and see how you go. If you cannot get this bullet to work, you may be near the end of the line. Jump wise, go for either kissing the lands or 10 thou to begin with. I do find some rifles like the ELD-X on the lands so long as this can be done without the throat pulling your loads if you have to extract.

There could be other factors at play here. It is always hard for me to say when I do not have the rifle in hand. Just don't let people fool you with fancy talk. The evidence is in the groups you are shooting, not some twist rate calculator.

If Hornady do not announce a heavy 190-195gr by the end of the first week of November and if your barrel is getting worse, then this would be the time to pull it.
06 Aug 2018
@ 02:11 pm (GMT)

Jim Moseley

Re: 180 ELD-M Instability?
I'm not one for wasting time, money or barrel rd count. I'll just go back the what works just fine and that's the 162 amax. The load for the new ELDM should be close to the standard amax. I have one box of the old ones to use first. Thanks Nate. Hope all is well with you.

Jim
11 Aug 2018
@ 02:15 am (GMT)

Charles Turner

Re: 180 ELD-M Instability?
Another thing to look at is cocentricity. Nathan has mentioned it somewhere here or in a book, but basically these bullets can require a VLD seating stem. Otherwise due the their length they can be seated via the tip rather than ogive/burley body or whatever is normal.
Hornady make bullet specific seatingt stems FYI.
12 Aug 2018
@ 01:46 am (GMT)

Paul Leverman

Re: 180 ELD-M Instability?
"Since 2011 I have been warning against the 8 twist 7mm but I am just one voice versus many who disagree and make a lot of noise doing it. So I guess I'll just keep shooting my accurate rifles while they can carry on shooting their inaccurate rifles and making up bullshit stories about bullets changing directions before they go to sleep."

Too bad that won't fit on a bumper sticker.
12 Aug 2018
@ 12:21 pm (GMT)

Warwick Marflitt

Re: 180 ELD-M Instability?
Hey Paul. There is a bumper sticker. It says.
"To live a good life, make good choices".
12 Aug 2018
@ 12:28 pm (GMT)

Warwick Marflitt

Re: 180 ELD-M Instability?
Nathan it's like trying to teach people how to sharpen a drill bit. Its impossible when their minds are blunter than the bit we're trying to get sharp?
13 Aug 2018
@ 07:51 am (GMT)

Nathan Foster

Re: 180 ELD-M Instability?
Folk just try to do the best they can. They might read my work and think yes maybe he has a point, but then when they visit their gunsmith, the smith talks about how "you can't overstabilize". So they have two options, listen to the guy some thousands of miles away who they have never actually met in person, or listen to the smith in front of them who speaks adamantly and is backed by a match bullet maker and various publications. Its not easy for the customer.

14 Aug 2018
@ 01:08 pm (GMT)

Jim Moseley

Re: 180 ELD-M Instability?
My cousin has a 7 mag with a 9 twist, so I think I'll test the 180's in his rifle and see how it performs. Thanks for all the feedback guys.

Jim
 

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