Anyone reload for a glock? Some observations.

[jpuke]

I recently started reloading for my glock 20 in 10mm auto.  I'm an experienced handloader with 1911's, Sigs, Blackhawks, 30-06, etc.
Anyway, I have been using data from the Hodgdon free manual (2006) with Longshot powder and my results have near duplicated their data - 180 gr bullet @1289 fps with 9.5 gr of Longshot.  (I'm getting 1310 fps in my aftermarket Storm Lake barrel, with a supported chamber)  My question is regarding primer pressure signs with Glocks.  The fired cases that came with the gun are Blazer aluminum stuff with a normal looking firing pin strike on the primer, no flattening.  My cases have a fairly flattened primer, not so much that they are flush with the case head, but enough that there's a distinct squared protrusion from the firing pin hole in every primer.  I was worried that these loads are too hot but the exact same thing happens when I use the same bullet @ 1150 fps.  Is this common to Glocks?  I rarely use max loads and I'm hoping to get out of this cartridge what it was designed for. 

[sui generis]

And what brand of primers are you using?

CCI = hard

Federal = soft

others kind of in between.

Federal will flatten with fairly mild loads (as in standard pressure .38Spl)

[MnMike]

There is a caution on some 10mm guns that do not fully suport the case (the ramp is unsuported). I seem to think that the Glock imay be one of them. This caution says to not reload. The case can take one fireing but if the second happens to align with the first, there could be a blowout at the unsupported point. I know my gun has an unsupported area at the ramp. I have seen bulges at this area with maximum loads. Resizing eliminates the bulges  but the case is still weakend. I now only reload with new cases.

mike

[jpuke]

I am using CCI 300 primers and the chamber of my aftermarket barrel is better supported near the ramp than the factory original.  I noticed that the brass fired in the factory barrel is a lot harder to size than those fired in the aftermarket barrel.  The new barrel is the only one that I shoot now.  (The funny thing is that the Hodgdon manual has a warning about the 40 S&W without fully supported chambers but nothing for the 10mm)  I guess my biggest question is whether the Glock being fired by a striker is different than a normal firing pin being hit by a hammer and if that can change the look of a fired primer.

[mbartel]

I have a G21 .45acp that does the same thing around the firing pin indentation. Even with mild standard factory ammo. The rectangular shaped striker is somewhat tapered, and when fully extended into the primer, there is a little excessive room around it for the primer to "flow" into. The clearance around a straight round firing pin, doesn't change when the pin moves forward to hit the primer. I replaced my factory barrel with a 6" Jarvis barrel, and replaced the guide rod with a Sprinco reduced recoil dual spring guide rod. I shoot .45 Super ammo in mine now. The Texas Ammo .45 Super Express 185gr XTP loads run about 1520 fps down the Jarvis barrel and the primers look the same as the standard .45 acp loads...

[jpuke]

Thanks, mbartel.  Glad to see someone else has noticed the same thing.