Painless load development (mine)

[Eiden]

Threw together a load with this method.

Bullet seated to boat tail neck/shoulder junction. No clue how far it is off lands. 1/2gr below book max charge weight. Rounds shot in 5 shot strings letting the barrel cool between strings.




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[Helislacker]

so I was out today to try and work up a load for the 143gr ELD-X. I’m hoping to load one round that’ll meet power factor NRL Hunter and be used general hunting in 6.5. I quickly found out my Tikka much prefers the 140 ELD at anything over 41.0gr of H4350 both in terms of accuracy and pressure. With the 143’s at 41.5gr I had a slightly stiff bolt, at 41.7 grains I had a very stiff bolt, primer cratering and other issues. No bueno, especially compared to the 140 at the same speeds.

So I went back to my old faithful 42.0g H4350 140 ELDM load and shot some drills, as well as a few groups off bags. I’ve put about 250 rounds through my gun with this load so far without issue. No cratering, no obvious ejector marks, no stiff bolt. Then out of nowhere I blew a primer - and spent 15 minutes trying to get the brass out of the gun.

Immediately afterwards I confirmed there were no barrel obstructions and shot some factory ammo. No issues. I went back to the 42.0g load and shot a few more…..no issues.

I’ve attached photos of the brass, including the blown primer for reference.

What do you guys think? Time to back off a half grain or so? Or keep going - chalk it up to more of a one off type situation? Again I’ve shot this load quite a bit, never even had a stiff bolt or a slight primer crater.

 

[HairyScandinavian]

so I was out today to try and work up a load for the 143gr ELD-X. I’m hoping to load one round that’ll meet power factor NRL Hunter and be used general hunting in 6.5. I quickly found out my Tikka much prefers the 140 ELD at anything over 41.0gr of H4350 both in terms of accuracy and pressure. With the 143’s at 41.5gr I had a slightly stiff bolt, at 41.7 grains I had a very stiff bolt, primer cratering and other issues. No bueno, especially compared to the 140 at the same speeds.

So I went back to my old faithful 42.0g H4350 140 ELDM load and shot some drills, as well as a few groups off bags. I’ve put about 250 rounds through my gun with this load so far without issue. No cratering, no obvious ejector marks, no stiff bolt. Then out of nowhere I blew a primer - and spent 15 minutes trying to get the brass out of the gun.

Immediately afterwards I confirmed there were no barrel obstructions and shot some factory ammo. No issues. I went back to the 42.0g load and shot a few more…..no issues.

I’ve attached photos of the brass, including the blown primer for reference.

What do you guys think? Time to back off a half grain or so? Or keep going - chalk it up to more of a one off type situation? Again I’ve shot this load quite a bit, never even had a stiff bolt or a slight primer crater.

Just that one eh? Wonder if primer wasn't seated fully or loose primer pocket. I don't have enough experience to comment so in to see what others say.

 

[Nine Banger]

Are you using a powder drop? If so, you probably had a light charge and then the heavy charge in drop sequence.

 

[Helislacker]

Just that one eh? Wonder if primer wasn't seated fully or loose primer pocket. I don't have enough experience to comment so in to see what others say.

Just the one. It would have made more sense if there were prior pressure signs that I ignored, but I’ve been pretty diligent. I knew the 143gr 41.7gr load was hot right away because of the stiff bolts, so I stopped shooting there. The 42.0g 140 load has been like shooting factory in terms of bolt lift and brass indicators until this one.

 

[Helislacker]

Are you using a powder drop? If so, you probably had a light charge and then the heavy charge in drop sequence.

No, I’ve got an electronic dispenser.

 

[Harvey_NW]

No, I’ve got an electronic dispenser.

That's not a fail-safe, they can still deviate quite a bit. But if you're so close to the edge that .2/3 causes heavy ejector stamp and primer pockets to let loose, I'd redo some pressure testing to be safe. It does seem like something happened though.

Brass for that load all fireformed and FL sized?
Any chance you had a magnum or different brand primer slip into the mix?

 

[Nine Banger]

That's not a fail-safe, they can still deviate quite a bit. But if you're so close to the edge that .2/3 causes heavy ejector stamp and primer pockets to let loose, I'd redo some pressure testing to be safe. It does seem like something happened though.

I was thinking, if 143 ELDX spikes out lower than that load, why would this new load in question be within pressure? bearing surface? Or logic dictates its not?

 

[Harvey_NW]

I was thinking, if 143 ELDX spikes out lower than that load, why would this new load in question be within pressure? bearing surface? Or logic dictates its not?

Bearing surface of M's are wildly shorter than X. I goofed up thinking they would be close and throated a 7 PRC for the 180 ELD-M being ~.050" off lands seated boat tail edge to neck shoulder junction, and then wanted to shoot the X instead for the larger nose opening behind the tip. This is at the lands with the 175 ELD-X. Honestly thought I was doing something wrong at first.

 

[Nine Banger]

Bearing surface of M's are wildly shorter than X.

I just had a similar experience with 107gr and 116gr TMK. The same amount of powder makes the 116gr go faster.

 

[nm.otter]

Not familiar with the 7mm slugs, but IIRC the 143 ELD-X is similar to the 147 ELD-M in shape.

 

[Harvey_NW]

Not familiar with the 7mm slugs, but IIRC the 143 ELD-X is similar to the 147 ELD-M in shape.

Meant to edit my post so it was specific to those 7's and not a blanket statement, hadn't finished my coffee and got handed a job..

I do know that I had to have my factory Tikka chamber throated out a ways to get a 143 to the same spot of boat tail at neck/shoulder being .050" off the lands. But scanning the interwebs real quick I'm seeing the bearing surfaces lengths of 140 being cited at .415", 143 ELD-X at .467", and the 147 M being either .535" or .585". So I would expect the 140's to be lower pressure at the same charge. But I'm still confused about how the 6.5's are almost opposite of the 7's..

 

[Helislacker]

That's not a fail-safe, they can still deviate quite a bit. But if you're so close to the edge that .2/3 causes heavy ejector stamp and primer pockets to let loose, I'd redo some pressure testing to be safe. It does seem like something happened though.

Brass for that load all fireformed and FL sized?
Any chance you had a magnum or different brand primer slip into the mix?

It was all once fired Hornady brass. Resized and put through a tumbler. I don’t have any magnum primers so that wouldn’t have been it either.

It just seems odd that if I’m so close to the edge that I’m blowing primers, why am I not seeing even subtle primer cratering or swipe marks? When you look at the brass in those photos are you seeing something I’m not?

 

[mlevimadden]

It was all once fired Hornady brass. Resized and put through a tumbler. I don’t have any magnum primers so that wouldn’t have been it either.

It just seems odd that if I’m so close to the edge that I’m blowing primers, why am I not seeing even subtle primer cratering or swipe marks? When you look at the brass in those photos are you seeing something I’m not?

I'm not seeing any high pressure flags on your other brass. Did you check the length of the casing that blew the primer after firing? Having a long one that hit the end of the chamber neck will definitely give you a pressure spike. You could also check the headspace isn't significantly shorter than all the others, but it probably made it to the chamber walls after firing given the high pressure event.

 

[Harvey_NW]

It just seems odd that if I’m so close to the edge that I’m blowing primers, why am I not seeing even subtle primer cratering or swipe marks? When you look at the brass in those photos are you seeing something I’m not?

No all the other headstamps look fine. Although bolt lift is a much better indicator, I typically see ejector stamp and/or swipe when it gets to that point. Going from no signs to popped primer makes me think something happened. H4350 isn't very chunky but if the hole in your powder funnel is small I've seen powder jam that can end up in the next case. Or if you threw a mischarge and then dumped it and recharged, sometimes the grains get stuck around the flash hole and take quite a smack to get them all out. Wet case, or forget to wipe lube off that one?

 

[Helislacker]

No all the other headstamps look fine. Although bolt lift is a much better indicator, I typically see ejector stamp and/or swipe when it gets to that point. Going from no signs to popped primer makes me think something happened. H4350 isn't very chunky but if the hole in your powder funnel is small I've seen powder jam that can end up in the next case. Or if you threw a mischarge and then dumped it and recharged, sometimes the grains get stuck around the flash hole and take quite a smack to get them all out. Wet case, or forget to wipe lube off that one?

Possibly. Either that or maybe some tumbling media (aka sushi rice) got left behind in the case causing pressure issues. Either way I’m going to carry on and keep shooting this load.

And yeah, you don’t know what you don’t know, but I know what bolt lift and cratering feel/look like. The 41.7g 143 load had obvious signs of that but still wasn’t blowing primers. This load doesn’t have those issues.