Hot 9mmP using book load

[Camba]

Hi everyone!

I decided to reload some 9mmP to shoot with my CZ75BD and Glock 17L.  The load was a Speer GDHP, 124 gr on top of 6.00gr of Unique.  The LEE reloading manual says the max load is 6.2 grains while the Speer loading manual said 5.9 gr.  I used 6.00grs for this load.  I measured my powder load using an RCBS automatic powder measure with the attached RCBS1500 scale.

I went to the range to see the accuracy and I decided to bring along an old Chrony.  I started with the CZ75BD and a five shot string gave me an average of 1265 fps and it showed good accuracy as well.  Then, I tried the Glock 17L and I've got 1318fps avg.  The Glock was not as accurate from the bench but it was better off hands.  Then I remember that the load that I was trying to achieve was supposed to go to about 1150fps max. I quit shooting because something did not look right.  Either the Chrony was wrong or the load is hotter than advertized.  I did not see signs of heavy pressure in the spent cases of the CZ75BD but the spent cases from the Glock showed the print mark of the firing pin very clear (a rectangular mark with a concave dimple in the middle).  Do you think this powder may be a different powder with the Unique name on it?  Have you experienced the same load and got the same velocities as I did?

Camba

[sr sawyer]

Never start with max or near max loads.  Every handgun or rifle is different and that is why every reloading manual has a start load and you should begin with that load. 

I have a .243 that pierced primers with a load that was still 3.0 grains under max as listed in my loading manual.  If my starting load had been as close to max as yours I could have had a lot worse experience that just a pierced primer.

Start low and work up and all will be okay.  Cautious and alert reloaders still possess all of their appendages and eye sight.

Back off and start over.  The gun will likely survive better too    

[helotaxi]

Every Glock I've ever seen does that to the primer.  I don't have a Glock but a friend has two and gives me all his brass and I have a bag full of brass with primers just as you describe from factory ammo.  It's a result of the striker channel being much larger than the striker.  Are the edges of the primer flattened?  That would be more indicative of high pressure from that gun.

Also the rifling in the Glock barrels are conducive to a little extra velocity and you have the long barreled version which will increase the velocity even more.

The extra velocity could also be a result of the primers that you're using if they're not exactly the same as the ones called for in the load data.

[Camba]

Helotaxi:  The primers I used for this load were CCI-500 small pistol primers.  There was no sign of flattened primers from neither of the two pistols.
Because I love my two mentioned pistols for their accuracy and reliability, I decided to heed Sr Swayer's comments.  I will start the reloading from low to high, keeping an eye on the pressure signs.
The question remains as far as the possibility of having a powder that may be hotter than we are aware of.

Thank you for your comments.

Camba

[the great orator]

What you described is Glock's "trademark" (kidding) striker imprint on each and every primer from every caliber.  it's not a problem with pressure.  Pressure signs would be your popped primers, flattened primers, blown primers, hard extractions, etc., but if that's all you're getting, you're still good.  I'd still start at the lower end of the powder scale and work your way up.  Sometimes rounds shoot better with less powder, which is a win-win, considering the cost and availability these days....