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Crater too deep on primers?


ChemistShooter

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I am experimenting with Power Pistol. The top three are my normal load, 3.9gr TiteGroup using .356 Eggleston 115gr OAL 1.149. The bottom two are the same except using 5.0 gr Power Pistol.

 

The Power Pistol primer pits are definitely bigger, maybe twice as much. No rim on the pits but definitely bigger. No question the brass is hitting  the striker a lot harder.

Too much? The weird thing is the kick didn't feel any different. I also noticed a bright white flash.

Power Pistol test.png

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2 hours ago, ChemistShooter said:

I am experimenting with Power Pistol. The top three are my normal load, 3.9gr TiteGroup using .356 Eggleston 115gr OAL 1.149. The bottom two are the same except using 5.0 gr Power Pistol.

 

The Power Pistol primer pits are definitely bigger, maybe twice as much. No rim on the pits but definitely bigger. No question the brass is hitting  the striker a lot harder.

Too much? The weird thing is the kick didn't feel any different. I also noticed a bright white flash.

Power Pistol test.png

Bright white flash is a trademark of PP. lol

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Hmmm. If the load is 5.0 grains of Power Pistol under a 115 gr. bullet, that is a rather light load. I would expect dirty cases at that pressure more than likely. What you usually look for with primers is cratering around the firing pin strike and flattening of the primer near the edges. I see none of that in your photos. Please note, that these pressure signs are not to be relied on - harder primers will show pressure signs later, and by the time you see flattening, you are already getting up there pressure wise. 

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Fired out of an XDM 9mm 3.8 Full-Size.

Not chronoed. This was the first test load to see if the charge would cycle the gun. I used Lyman lead data to estimate a load.

 

Yeah, the brass on top is FC but Blazer with that load looks exactly the same as the FC. The PP crater difference is due to the PP.

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I load 5gr Pwr Pistol for 1039-1043 fps w/124 RN. Gives 127-129 PF. For IDPA/USPSA match power factor. 5.6 is awesome accuracy which I load for longer range KD's. Bit more punch but not noticeable at run speeds.

Sent from my SM-G935V using Tapatalk

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On 3/7/2017 at 3:51 PM, xxkingxx said:

I load 5gr Pwr Pistol for 1039-1043 fps w/124 RN. Gives 127-129 PF. For IDPA/USPSA match power factor. 5.6 is awesome accuracy which I load for longer range KD's. Bit more punch but not noticeable at run speeds.

Sent from my SM-G935V using Tapatalk
 

Yeah, my minor load is 5.2gr PP with a 124 rn. 5.0gr is crazy light with a 115. My kind of regular load for a 115 HP was 6.0gr PP, a full grain higher than what you've got going, OP.

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Cases are not the same, weigh them and you will see. So with two different cases, you can't compare them because the primer will seat differently. What primer? And 5 grains of PP is very very light. Here is what real pressure looks like on the right

 

 

image37184.jpg

 

 

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Chem, how clean was that brass before firing? Dirty cases are also a sign of too light of a load. By the way, dem Egglestons is some ugly looking bullets, ok, they are polycoated, and not HiTek (good looking bullets). Bayous is clean.

 

453045479.jpg

 

image37460.jpg

Edited by 9x45
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19 hours ago, superdude said:

Chemistshooter, based on the responses, have you determined the answer to your question?

Yeah, I think so.Got a little bit of a crater but the primers are not flattened. Going to eventually make another pass with the same load and matched cases. Might set up the chrono for this one, keeping in mind you can still have overpressures even with what looks like light loads.

I sorta wonder what a set-up to measure CUPs would cost. I make my living handling gadgets like that.

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9 minutes ago, ChemistShooter said:

Yeah, I think so.Got a little bit of a crater but the primers are not flattened. Going to eventually make another pass with the same load and matched cases. Might set up the chrono for this one, keeping in mind you can still have overpressures even with what looks like light loads.

I sorta wonder what a set-up to measure CUPs would cost. I make my living handling gadgets like that.

 

Your load is very, very light. The odds of 5.0 gr of PP and a 115 grain bullet at 1.149" being overpressure are close to zero.  5.0 gr is just above the start load in the Hornady manual for 115 gr jacketed bullets, and they top out at 6.7 gr.  The Alliant manual shows 6.7 gr as max with a 115 grain bullet. You're on the low end of pressure.  

 

 

With respect to CUP measurements, you might find this information useful if you don't already have it...

http://saami.org/specifications_and_information/publications/download/Z299-3_ANSI-SAAMI _CFPandR.pdf#page=10

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24 minutes ago, 57K said:

 

 

 

The thing about CUP testing is that it's about finding Max Pressure, while the piezoelectric transducer in the PSI systems look at the total spectrum of Pressure/Time from ignition to Max Pressure. There's been debate about which is best yet some component makers have switched back to the CUP method. One reason we have 2 different pressure standards for the 9 x 19mm. 35,000 PSI and 33,000 CUP. Their essentially the same Max pressure.

 

Who has switched back to the CUP method?

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23 hours ago, superdude said:

 

Your load is very, very light. The odds of 5.0 gr of PP and a 115 grain bullet at 1.149" being overpressure are close to zero.  5.0 gr is just above the start load in the Hornady manual for 115 gr jacketed bullets, and they top out at 6.7 gr.  The Alliant manual shows 6.7 gr as max with a 115 grain bullet. You're on the low end of pressure.  

 

 

With respect to CUP measurements, you might find this information useful if you don't already have it...

http://saami.org/specifications_and_information/publications/download/Z299-3_ANSI-SAAMI _CFPandR.pdf#page=10

I know it was supposed to be light. The depth of the primer had me feeling a little paranoid, though.

Thanks for the link.

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