Hornady 140 ELDM Changes

[NHPiper]

So I found out the hard way a couple lessons about reloading .260 Remington today after I started experiencing case head seperations. I can attribute it to weakening brass and also dimension changes by Hornady with their 140gr ELDM bullets. Their base to ogive increased by +0.037 when they started using the solid red tips again, which forced my bullets into the lands causing a pressure spike (originally a +0.020 jump). The OAL falls within magazine length. I noticed increases tightness when chambering in my Rem700 and when extracting rounds identified rifling on the bullets. Loaded over H4350 with 43.5gr.

Lessons learned:

1. Don't buy used brass (even Lapua)
2. Remeasure bullets anytime tips change color (Hornady said dimensions didn't change)
3. Pay attention to discoloration and stress lines
4. Check internal brass thickness especially near the base

This brass had been annealed once after my 2nd time of firing and had about 5-6 firings by me (guessing 3+ by others).

 

[morganlamprecht]

Measure your rounds from cartridge base to ogive and that won't be an issue...all bullets have lot to lot variations like that

 

[Rob01]

You should check any bullet when changing lots as there can be some variations. Nothing to do with tip color. The color only changed due to a possible infringement on another maker with the translucent tip.

The case head seperations come from from over working the brass. You need to get a headspace gauge and measure how much you are bumping the shoulder. Shouldn't be more than .001-002".

 

[padom]

+1 to everything said above

Tips have zero to do with your issue. If you are bumping your brass back .001-.002 from fired case headspace and measuring base to ogive vs COAL and checking new lots of bullets you wont have these issues.

 

[DI Precision]

What is your muzzle velocity at 43.5 gr?

 

[Ledzep]

Yep, echoes of everyone else. I swapped my last .260 barrel at 2200-2300 rounds in favor of trying a 6.5 SAUM. I used the same 100 cases from start to finish, and they're still loaded with my pet load if/when I burn the SAUM barrel out I can throw the .260 back on. Bump the shoulder as little as you need to to get the bolt to close easy, anneal at least every 3 firings, and trim when you anneal to be safe.

I've made it a habit to buy what I estimate the useful round count of the barrel will be in bullets from the get-go (2000-3000 bullets up front all from the same lot). Any time anything changes it's good to double check, especially if you're running on the warm side of things.

 

[demolitionman]

Damn'it man! Thanks for sharing this. Keeps us all on our toes about our datum line bump measurements. Does anyone think maybe he should check that his chamber walls aren't way out of round on one side or that the breech face on his barrel and action are concentric to one another?

 

[Milo 2.5]

Damn'it man! Thanks for sharing this. Keeps us all on our toes about our datum line bump measurements. Does anyone think maybe he should check that his chamber walls aren't way out of round on one side or that the breech face on his barrel and action are concentric to one another?

It possibly could be, but there's a few indicators here, used brass, etc... The op is getting the "bump" blame when it could have been set in motion before he bought it. Buying used brass from guys shooting 6.5 creed factory ammo, (1 fired), not processed, in order to make coin to buy more ammo is one thing, buying brass from someone who has processed it a few times, a whole different issue unless you know the guy and his dedication.
There is a couple failures involved in what happened here. Anytime brass is close to coming apart, a faint lighter colored line is visible on the outside of the case in that spot, know what to look for.

 

[Rob01]

Yup depends on the history of the used brass. Once fired is fine as nothing could have been done short of shooting it in a bad head spaced chamber but anything past that is a crap shoot depending on the person who was loading it. From an experienced loader who knows how to bump shoulder correctly you would be fine but from someone who just cranks a die in and pulls a handle then you could get what you see above.

 

[NHPiper]

To be honest guys, I am kind of surprised by what happened. My brass is trimmed and hand inspected, and I don't think my shoulder bump was that bad. I am going to have to remeasure it this weekend. With the load, I am getting 2835 fps on average with 140 ELDMs. I think this is more of a pressure issue related to the bullets jamming too hard into the lands, but I could be wrong.

 

[ChiefW]

I noticed a major change in the ogive location on the same bullet from one lot to another. I load to ogive so it really didnt impact me that much, but was a suprise there was that big a difference.

 

[steve123]

Powder burn rate varies from lot to lot too. I toasted some brass before thinking the new 8lb jug was the same as the old one.

You mentioned annealing. Previous owner of brass could have basically ruined his brass by cooking it too long and weakening where the separation is, though that's the normal place it happens.

Bullets way into the lands could bring pressures up.

Brass was near the end of it's life when you got it.

Could be a tight neck reamer was used to chamber the rifle and unturned necks don't have any room for expansion.

Any combination or all combined.

 

[Sweetyzfd]

What seating die are you using? You really should be seating base to ogive not OAL. If you load for ogive you should diminish part of the problem you are having. Shouldn't just jam them into the lands