signs of overpressure

tedbeau

New member
I see a lot of post and here and else where and mention in loading manuals about watching for signs of overpressure but I have not seen any examples.

I know that a "Crushed" or flattened or pierced primer is supposed to be one, but I am not sure how to tell. Any one have pictures or a pierced or flattened primer? Also what are other signs of over pressure.

I do not plan on loading my round to anything above published, in fact I really am looking at loading light recoil loads for shooting IDPA in the new CCP division so lighter is better as long as it makes the minor power factor.

Still I would be interested in knowing what to watch for in overpressure signs.

Thanks
 
A flattened primer MAY or may not be a sign of overpressure in a handgun. Stick with published data and pay attention to seating depth and you shouldn't have anything to worry about.
 
pierced primer is supposed to be one,

The pierced primer is one of those .7854 things. The firing pin spring must produce enough pressure to overcome the pressure inside the primer. First there is the dent, then there is the conforming meaning the primer conforms to the protruding firing pin.

There are twilight zones, hammers/firing pins have been know to bounce.

F. Guffey
 
Still I would be interested in knowing what to watch for in overpressure signs.

Lost is the art, in the big inning it went something like "THE BEGINNING SIGNS OF HIGH PRESSURE". Measure before and again after. Case head expansion, problem: When compared to 'WHAT?'. When compared to the case head diameter before it was fired and compared to new factory over the counter ammo. A number that jumps our is .00025".

then there is the relativity theory. If the case head expands so does the flash hole and the primer pocket. Very few measure the diameter of the flash hole before and again after. we are not talking about every case, we are talking about developing a load.

Then there is the case head crush, That is another .7854 thing. Then there is case stretch, I am the fan of cutting down on all that case travel. Problem 'all that case travel' takes too much time to explain.

F. Guffey
 
Thanks, I think

Ok, maybe I wasn't clear, I am new to reloading, so what is the .7854 thing referring to?

I have a grasp on to light a pressure, in that the case fails to expand and seal the chamber so you get excessive blackening on the outside of the case. I was able to create this by running some really light loads in my glock. I suppose the fact that a glock chamber is pretty loose to begin with contributes to this condition. I don't plan on loading any more that light because I am sure they would not meet power factor even though they did cycle the gun OK.

I guess I will have to run loads up toward to high end and examine the cases and primers myself to see if I can see where they appear to start to change.
 
We tend to look for different things to identify pressure in different platforms.

In revolvers, the biggest red flag is difficult extraction/ejection.
In pistols, it is bulged or battered brass and cases being chucked MUCH further than you typically expect with that handgun.

Looking at primers is an art, and it takes experience to get a feel, but please save yourself unnecessary frustration by keeping this in mind when attempting to read primers:

it's all relative
look at fired primers at the low end of your work up and compare them to what you observe on the high end of your work up and compare THOSE

To look at a .380 fired primer and try to gain insight in comparison to your .40 S&W primer is nonsense. And in fact, looking at your .380 load with SuperBlast powder and ACME primer under a ThudCo bullet in a CCI case and comparing that to a fired Winchester factory .380 round also tells you almost zero.
 
Still I would be interested in knowing what to watch for in overpressure signs.

Do you have a manual from one of the major reloading companies? Not only do they print pictures of overpressure, they list many signs. If you are just using loading info from online sources, highly recommend buying a reloading manual and reading it.
 
I keep a summary list of pressure signs here. I'll see if I can copy it to this board without anyone's panties getting into a bunch.

Exactly what I was looking for. Thank you.
 
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