Progressive Pressure Signs

[Airw4ves]

While doing load development, I noticed my loads began to show signs of primer cratering and ejector sweep after 15+ rounds. These were done 5 at a time then the bbl allowed to cool. I had no issue with my previous development, and similar velocity so it surprises me to see these. Im definitely no pro when it comes to pressure signs, but 37.3 - 37.6gr Varget out of a 23” bbl 6.5x47L shouldnt be too excessive. I can always back it down but Im not reaching the velocity Id like in the next node
If anyone has input Id appreciate it.

 

[redneckbmxer24]

What bullet? If it's a 140 that's definitely up there in pressure. I had a node at 37.3gr also but got the same light pressure signs but decided the 50fps wasn't worth trashing my brass so I'm running 36.8gr.

 

[Airw4ves]

Yeah 140 ELD-X

 

[redneckbmxer24]

Just back down to the next node. Velocity isn’t everything.

 

[Airw4ves]

Sounds good!
Thanks for the help

 

[EchoDeltaSierra]

Assuming you’re comfortable and competent with what you’re doing (and I assume you are), if this were my brass I’d push it further. I generally find my top nodes start to flatten the primer a noticeable bit.

This is a few pieces from my comp load which is a 140 ELD just shy of 2800fps out of a 21” 6.5CR barrel (trued velocity w/ SiCo Omega installed).

Also, velocity isn’t everything, but it is nice.

 

[Strykervet]

Yeah, for some reason when we load we always want the maximum velocity and what not... Or at least "up there". But I had it put to me that if I needed to do that, then I should just upgrade to the next more powerful cartridge that'll give me that on the lower end of the loading spectrum.

It made sense and I've been trying to abide by it since. Barrels in general fair much better.

But some loads do perform better at the upper end of the loading spectrum, the higher end of the data, just gotta be careful. I don't like loads that show pressure signs, period, because chances are there are worse conditions than the one you're testing in where it could go from a sign to a problem.

So yeah, that's good advice there. If there's a powder that'll achieve more velocity, you can always try that too. I know some different mfg.'s can be as much as a few hundred fps with the otherwise exact same load.

 

[redneckbmxer24]

Assuming you’re comfortable and competent with what you’re doing (and I assume you are), if this were my brass I’d push it further. I generally find my top nodes start to flatten the primer a noticeable bit.

This is a few pieces from my comp load which is a 140 ELD just shy of 2800fps out of a 21” 6.5CR barrel (trued velocity w/ SiCo Omega installed).

Also, velocity isn’t everything, but it is nice.

View attachment 6991341

The issue isn’t flattened primers, that isn’t a good way to tell pressure. Very low pressure loads can flatten primers especially if the brass is a bit short in the chamber. The issue is the ejector swipes which is a good way to tell pressure.

Those swipes are indication that the brass is going to wear out at the primer pocket faster, and he may have worse pressure issues on hotter days or if a little rain gets in the chamber. Neither are worth a few extra FPS.

 

[EchoDeltaSierra]

Those swipes are indication that the brass is going to wear out at the primer pocket faster, and he may have worse pressure issues on hotter days or if a little rain gets in the chamber. Neither are worth a few extra FPS.

That is absolutely correct. I’ll be testing and closely monitoring the load I cited as seasonal temperatures rise again. Though on several rifles I’ve found nice loads in the “.2 grain under compressed” range. (Just make damn sure you’re paying close attention to what’s going on.)

I also have a nice training and fun-match load I run at 2640fps out of the same rifle. There’s nothing wrong with backing off some.

 

[Milo 2.5]

Lapua 6.5x47 brass does not cough up pressure signs easily. If your brass is not growing lengthwise and getting slammed into your bolt face, you're into pressure. Back it down or find a slower powder to achieve your velocity wanted.
You can never go off primers for pressure signs on new brass, the brass is not chamber length, and upon firing, it takes a lot less pressure to kick the primer out of it's pocket than sending a bullet down the bore, hence flat primers. Cratering or rupturing, < that all depends on the degree of the symptoms.