I admit I don't know too many details about the different brands of ammunition, but wanted to use what would be considered high quality ammo in the gun that I carry and in the one that is my primary home defense handgun. In 9mm, I have both Speer and Hornady Critical Defense. Normally at the range I use cheaper ball ammo rather than JHP and both my carry gun (LC9s) and my home gun (Glock 17) seem to accept everything that I have put in them regardless of type or brand, as long as I get the caliber right! But today, firing my Glock 17, I decided to shoot some of the "better" ammo just to see if it felt any different than the cheap stuff. About the 3rd round I knew something was not right as soon as it fired. It sounded like a less than normal powder load, and while the bullet fired, the gun did not cycle. I assumed it was a one off, and it clearly was not the gun at issue, so I continued shooting. Within the same magazine it happened twice more. When I checked what was still in the magazine it was a mixture of both Hornady and Speer, and since there were tons of cases on the ground all around me I could not be sure what brand the mis fires had been. But it did give me a bit of pause, thinking that had I been in a self defense situation this could have been a matter of life and death. Now I'm just now sure what I should be keeping in these two "always ready" handguns.