Sign of over-pressure? (Pic)

[November]

These were 9mm loaded with 124 grain FMJ, CCI 500 small primers and the powder used was Unique. Mixed brass and COAL was 1.155 to 1.16. Fired in 3 different semi-autos. All fed, fired and ejected just fine. Good power and accurate, too. None of the cases bulged, but the primer looks "flattened" to me. Do the primers look like they exhibit signs of over-pressure?

 

[Jim Puke]

It looks like pressure, to me. You also have some pierced primers in that group.

 

[November]

It looks like pressure, to me. You also have some pierced primers in that group.

No pierced primers, just looks that way due to the poor lighting.

 

[Cheesewhiz]

Let me guess, a Glock, another striker fired gun, maybe a Ruger LC9 and a hammer fired gun, probably a Smith by the firing pin hole size.

I think the shadows make it look like they are pierced but they are CCI's and hard so looking at them won't give the tell that some others may show. Looking at primers for pressure signs isn't the best way to find if that is the case, JMHO.

 

[November]

Let me guess, a Glock, another striker fired gun, maybe a Ruger LC9 and a hammer fired gun, probably a Smith by the firing pin hole size.

I think the shadows make it look like they are pierced but they are CCI's and hard so looking at them won't give the tell that some others may show. Looking at primers for pressure signs isn't the best way to find if that is the case, JMHO.

Good guess! A Glock, an S&W SD9VE (which is striker-fired) and a Ruger P94.

 

[427mach1]

The primers don't look flattened at all to me. The edge of the primer is still very well rounded. A flattened primer will be completely squared off around the edges. How much powder were you using and what did the manual say min and max loads should be?

 

[November]

The primers don't look flattened at all to me. The edge of the primer is still very well rounded. A flattened primer will be completely squared off around the edges. How much powder were you using and what did the manual say min and max loads should be?

More than 5.0 grains and less than 5.4 grains of powder. I believe 5.8 is the max.

 

[ra]

As 427mach1 said the primers are not flattened, the radius on the corner is still rounded. If they where flattened the primer would fill the complete pocket.
Also the 9MM is a high pressure round, I have seen factory loads with the primers flattened.

Roger

 

[Chuck 100 yd]

No high pressure there as far as I can see. The rounded edges of the primers seem to be unchanged from the way they were made.

 

[wizofwas]

No high pressure there as far as I can see. The rounded edges of the primers seem to be unchanged from the way they were made.

I agree.

 

[Jimbo357mag]

http://www.massreloading.com/reading_pressure_signs.html



The Severely Flattened Primer On The Right Indicates That The Load Was Too Hot

 

[WIL TERRY]

NO ! They do not show excess pressures. They do sort of show a weak fing pin spring perhaps. What were the velocity spreads on all the loads tested ?

 

[jbntx]

ALL the primers in the OP's picture look perfectly normal.

 

[November]

Thanks all. Message received: primers look fine. It was my first batch of 9mm, so I wasn't sure.

NO ! They do not show excess pressures. They do sort of show a weak fing pin spring perhaps. What were the velocity spreads on all the loads tested ?

I don't own a chrony yet, so I have no idea unfortunately.

 

[November]

Thanks for all the info 57K. Unique is all I've got at the moment, but hopefully someday soon the other powders will be available locally to me. I will check out the Caldwell, do you have a model number?

 

[Sin6Sec63451022]

No expert here, by any means, but they all seem to be okay except there are some that look like the primers got pushed out a little bit. In jimbo's pic it appears to me that the left one is about right and the right 2 exhibit progressively higher pressures.

 

[Kevin]

I don't understand why the higher pressure sour flatten a primer? I can clearly see in Jim's picture of the three 357 rounds. But wouldn't the case bulge and stick in the chamber first? Or what? Does the case get slammed back into the pistol itself and somehow mash the primer?

Are the brass cases still useable after the primer has been flattened? I've just never seen one.

 

[Jimbo357mag]

I don't understand why the higher pressure sour flatten a primer? I can clearly see in Jim's picture of the three 357 rounds. But wouldn't the case bulge and stick in the chamber first? Or what? Does the case get slammed back into the pistol itself and somehow mash the primer?

Are the brass cases still useable after the primer has been flattened? I've just never seen one.

The primers actually move out of the case some and then back into the case when fired. At first when the primer is struck with the firing pin the primer moves backward against the breech face because of the initial pressure of the primer. With any normal load the case head and primer is pushed back against the breech face and flattened slightly. When there is excess pressure the primer cup can be pushed back even more and deformed to fill any space there is and be as flat as those that the pictures show. Excess pressure will expand the cases and sometimes they will stick in the chamber or cylinder. Flattened primers are a pretty good sign of pressure but not a guarantee same as sticky cases. The best way to determine excess pressure is with a chronograph. (as a general rule) You can't get more velocity without more pressure.

Cases that have had numerous Max. loads should be retired to the low pressure side of the reloading curve.

Incidentally very light loads can leave a primer cup sticking out of the case and bind up a cylinder from rotating. That is why when shooting blanks or wax bullets the primer hole is enlarged in the case so the primer cup won't move backward and bind up the gun.

 

[greenmtnguy]

I agree with the other fellas - those primers don't show excessive pressure, but one shouldn't rely only on primer appearances either.

 

[Chief 101]

Nothing wrong with Unique...