Ejector marks and pressure

[grinnergetter]

Would you consider any ejector mark a sign of too much pressure ?

What if primers are slightly flattened with no sign of cratering, bolt lift is normal, lets say that mark is very slight....would you continue testing with hotter loads?

 

[Garycrow]

It could be a sign of several things, one of which is high pressure. It could also indicate oil in the chamber.

Trying to read pressure from looking at case heads is like reading tea leaves, it doesn't tell you much. Compare the velocity over a chronograph with known book velocities, that'll give you a much better idea of the pressure you're running than looking at the case head.

 

[MagnumManiac]

Would you consider any ejector mark a sign of too much pressure ?

What if primers are slightly flattened with no sign of cratering, bolt lift is normal, lets say that mark is very slight....would you continue testing with hotter loads?

Ejector marks, even slight marks, are a sign that brass is 'flowing' at that pressure level. If brass is flowing, the solid head will also be expanding causing primer pockets to enlarge. This expansion may only be .0002"-.0005", but, if continued at this level, primer pockets will be too large after 2-3 firings.

The ACTUAL pressure is not important, it's the brass cases ability to withstand the pressure level that counts.
Primer appearance means little. I have noted many times that ejector marks appear way before primers flatten in certain brands, and others flatten with no ejector marks or hard bolt lift.

It must be understood that soft brass expands at lower pressure than harder brass.
I've had factory loaded Federal cases have ejector marks and enlarged primer pockets on firing them with factory loads. It is soft brass.

Hope this helps.

Cheers.
gun)

 

[grinnergetter]

Garycrow, my issue with speed and comparing is my particular rifle shoots much slower than others. 338 Edge doing 2670 with 250 rounds down the barrel.

MM, I have the same issue with Nosler and Bertran brass. 86.5 grains occasionally has marks but 87.0 always has very slight marks. Primers look identical between brands of brass. This load is way below what most folks are running. Bolt lift is normal.

I have measured everything a bazillion times making sure I have the correct clearances and die adjustments for brass and OAL etc.

 

[FearNoWind]

....would you continue testing with hotter loads?

I am baffled with this "hotter load" obsession that seems to becoming more popular all the time. Somehow the masses are beginning to believe the myth that "hotter is better" - it is not. Any increase in velocity achieved by pushing pressures to extremes (which seems to be the goal) is so slight it isn't worth the trouble.
Find the load that correspond with the node and you've got everything you need.
The "Tea Leaf Reading" analogy is a pretty darn good description. Cratered or pierced primers may or may not indicate overload. How "flat" does a primer have to be to indicate overload? Are all cases made of the same grade of copper - if not which might be softer/harder than the next and are the ejector marks on one a greater or lesser indicator of overload. Is a case that's hard to extract a sign of overload or just a dirty chamber, anomaly in case structure or some other factor?
End of rant .............

 

[grinnergetter]

Ha, please rant away! I by no means am after the "hotter load" and agree on the mention of node. As you can see my speeds and load are NOT the norm when it comes to this caliber...which is fine with me, just odd.

In my case, the rifle smith gave me a load of 92 grains that he tested to start with. ????????

Which, without a mentor or another super knowledgeable reloader leaves me second guessing myself.....ALOT

So...I hope that I explained my reasoning for the post better.

 

[Mikecr]

You won't ever know actual pressure, but you'll know pressure problems -when they are problems.
As far as pressure itself being too high, it's not a problem until it is.
Of course, you'll want to sneak into this and not go past it to a great big unrecoverable problem.

To me injector marks by themselves are not a pressure 'problem'. Primer flatness is not a problem. If my brass grows so much that extraction is difficult(popping extraction, difficult bolt lift), then that is a problem no matter the pressure. If extraction is fine, but growth has reached a point where my die can't handle it, that's a problem. If pockets are loosening, another problem.

 

[Rich Coyle]

Would you consider any ejector mark a sign of too much pressure ?

Yes.

What if primers are slightly flattened with no sign of cratering, bolt lift is normal, lets say that mark is very slight....would you continue testing with hotter loads?

No.

 

[grinnergetter]

Thanks for the responses everyone. I'll back it on down a bit and be happy.