10mm blowing primers - factory Hornady ammo

[jrothWA]

at my home range. Another member fired and left them, they are "mag-tech" 9mm brass. the most noticeable was the "rectangular" extrusion into the fire pin
passage. that would not allow the case to slide into the case holder for depriming.

Most semi's do not support completely the case during firing. So another factor most be addressed.

Good luck.

[Bongo Boy]

The photo posted by OP appears to be what I'd consider a fairly normal Glocked case in my experience with G20 and G29 only. I didn't see a photo of a post-mortem primer pocket, but that might be more informative. Is OP saying all 3 rounds blew the primers out of the cases?

I've had quite a good number of blown out primer pockets and blown primers with my own handloads, none of which have been beyond published maximums--at least to the best of my memory. All brass in those cases was Starline, which appeared to flow like butter.

I wouldn't have much reason to suspect a barrel--and as far as lock-up--chamber pressure is chamber pressure, and it's basically zero long before anything is unlocked AFAIK. You can certainly fire any auto pistol without allowing it to unlock at all--that doesn't do anything to change peak chamber pressure to the best of my understanding.

In any case, I'd agree that any ammo-firearm combination where the case is severely damaged isn't a good combination, and any combination where the case is allowed to deform to the extent the primers fall out is probably a poor, and potentially unsafe, combination.

I've thought for some time 10mm might be better off using small pistol primers and heftier brass.

I've never checked for setback--that would be worthwhile looking at.

[stagpanther]

I have a glock 20 which I have been using several 10mm barrels on for years--and of all the different barrels the lone wolf one seems to be the all-around best performer in terms of adapting to most off-the-shelf ammo as well as my reloads--which do sometimes explore the "outer limits" of full power loads.

10 mm is a tricky round that is immensely powerful for the small space you're jamming the powder and bullet into--in fact I think it really should be referred to as a magnum--but that's just my whimsical opinion. It might be possible that there is something wrong with the barrel--but what I have found is that if you remove the barrel prior to use and perform the "kerchunk" test you might be surprised at how much variation there is between ammo and case dimensions. Holding the barrel vertically, drop the rounds in and they should drop to the proper headspace clearance without any resistance--and also fall out when the barrel is inverted. My personal guess is that your issue is most likely cartridge related--and with the 10mm I could see how abnormal pressures--or chambering--could happen easily with only very slight variations in the cartridge dimensions. 4 to 6 inches isn't much length for a complete burn--my barrels can get fouled pretty easily depending on the powder used.

It can be hard--but listen for a difference in the report of the ignition. I once had a cartridge go off--sounded close to normal to me, and then the next round kept getting jammed. I re-racked it hard thinking that it was a feed issue--it was only after a couple of tries that it dawned on me to check the bore and sure enough a squib had lodged right in front of the case mouth datum--lucky for me it wasn't further in.

Your underwood loads are probably closer in pressure to what a "true" full power 10 mm is, while the Hornady--I'm guessing--is a more moderate load somewhere between a 40 sw and full power 10mm--but hornady is also skilled at often getting better performance with less pressure in their factory ammo I've noticed.

As usual--just my guesses.

[SansSouci]

Were I to find a Delta Elite, I cannot say I wouldn't buy it. But I've never been a fan of the 10MM. It generates a whole lot of pressure for marginal gain.

Besides, the .45 ACP has established a track record that'll never be whipped.