7mm Rem Mag flat primers?

[coyote223]

Is it normal? I loaded up some 160gr Nosler Partitions, IMR-4350, started at the min. All primers were flat. I don't know what primers were in the cases, as they were pre-primed. I've done enough loading to know that flat primers aren't a good sign, but flat at the min recommended loading kind of threw me. That and the accuracy sucked at the min. It is getting better the hotter I go, but,,,

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[Dallas Ken]

If I were you I would knock out any remaining primers and start over with something you know.

Good luck there....been loading 7mm mag. for years and my Rem. 700 got better as the loads increased. Then again the Rem. I had before got worse.

 

[Benihaus]

Yea remove the unknowns, then try with the data primer, also you may want to check your head spacing, perhaps you are compressing in chambering? I also really reccomend a lee factory crimp, made a world of differnce in consistency for me (I shoot a BAR though)
Ben

 

[Benihaus]

Were you using the Nosler data? They show 56.0 min 60.0 max with 4350, my load with the 160g accubonds is 66.0 gr of H1000 with cci LRM primers in my BAR with factory crimp.

 

[rick benjamin]

Flattened primers are one indication of excessive pressure.
For your own safety, invest in a chronograph. It will give you actual velocity.
Reduce the amount of IMR4350 until your primers look like they did before you shot them.
(except for the dimple in the middle)
I have used a Chrony for almost 40 years
Chrony F1
Recently bought a CED, it has a multi-shot buffer and control panel sits on my shooting bench
<broken link removed>

 

[Sabertooth]

Some primers have thinner shells so they will flatten easier, they are thin or soft enough that you can flatten them when you prime the case.

 

[jluck]

Pictures would help a lot. I don't worry about pressures with only flat primers, I look for other indicators along with them.

 

[Sabertooth]

I only start to worry when the primers crater. Provided the firearm does not have a history of cratering primers even with factory rounds.

 

[coyote223]

Thanks for the info. Managed to come across the last box of LRM primers at the store. So will try another load or two and see what "known" primers do with this powder,,,

Yes I plan on getting a chrony soon,,

 

[orygun]

Depends on the definition of "flat". My 30-06 flattens primers with factory Remington ammo. Even with starting loads and Winchester Magnum primers, the primers are flat, but no more so that when the loads are too hot and bolt lift/extraction is sticky.

Honestly, I don't think that's a great way to check rifle loads for pressure. 38 Special? Sure. 30-30? Maybe. Anything that operates at 50,000 CUP or higher? Nope.

 

[P7M13]

Sabertooth is dead on, IMO. The cratering in my primers when I'm running too hot looks like a ring around the water drop as it hits the surface. The real dead give away in my weatherby is the sticky bolt lift. But darn if the hotter loads didn't group better. I 2nd Benihaus's suggestion -- check your headspace.