Excessive pressure?

[jay2981]

These rounds are 115gn 9mm loaded with 6.4 grains of power pistol seated at 1.125 using S&B primers. The max load for power pistol 115gn 9 is 6.7. Is this a sign of excessive pressure?

 

[Double T]

I am thinking yes, from what I can see it looks like the primer is no longer flat but "rounded".

 

[Imeagher]

Not a very clear pic

 

[jay2981]

Sorry about the pic. They are uniform in size but raised around the firing strike. If excessive pressure but under max load could my bullet be seated to low at 1.125 causing higher pressures?

 

[Double T]

Depends on how much the powder is compressed in the case. If the primer is rounded and any different from "stock" it's a sign of overpressure. If that depth is what it takes to work reliably in your gun, then back off on the powder.

 

[BEANC0UNTER]

Mine look like that. Did you shoot that out of a XD? Mine does that on factory ammo too. Both my 9mm and 45mm

 

[jay2981]

Yeah I think I'll stick with the 6.2gn. Just wasn't absolutely sure about 6.4. I'm a bit surprised that it would be excessive then again compression I'm sure is the culprit. Thanks for the help!

 

[Broom_jm]

Looks an AWFUL lot like cratering, to me...but that pic makes impossible to be sure. If factory ammo, fired from that handgun, does not have primers that look that beat up then it's very likely those loads are a little too hot.

 

[Rob377]

115gr what? LRN? FMJ? JHP? What about crimp?

That amount of primer flow looks excessive, especially for well under book loading and hard as crap S&B primers.

Ensure your scale is properly calibrated. Check it again.

 

[jay2981]

Plated round nose. I ran about five charges that all came in at 6.4 before I started loading. I then checked the charge after loading the ten test rounds. The loads at 6.2 had very little if any cratering. Which leads me to believe I need to stay longer than the initial 1.125 oal.

 

[Rob377]

well, that, and plated bullets tend to perform more like lead when it comes to pressure. So the 6.7gr max is inapplicable here.

 

[MikeDVB]

Plated round nose. I ran about five charges that all came in at 6.4 before I started loading. I then checked the charge after loading the ten test rounds. The loads at 6.2 had very little if any cratering. Which leads me to believe I need to stay longer than the initial 1.125 oal.

Your load book/source should state the tested/suggested COAL. If you go shorter you're going to increase pressure.

 

[jay2981]

I should have stuck with the 1.135 from the book but a reputable loader shared his load which I used with this result. I have my second batch ready to shoot at 6.2 and the 1.135 to try now.