Wow, I just shot my 10mm for the 1st time today along with my .40 caliber. both are glocks, both are brand new, Now I am not sure what kind of 10mm ammo I was shooting because I inherited 30 rounds of unknown brand and I bought a box of 50 reloads @ some mom and pops gun shop for a reasonable price. I just have to say, the 10mm is NO joke!! there was definitely a noticeable difference in shooting the .40 cal. and the 10mm, matter of fact I had everybody @ the range watching and asking what I was shooting cuz it was so much louder then what everybody else was shooting. but, despite not knowing what kind of 10mm ammo it was, the muzzle flash was spectacular along with a much stronger shot then the .40 cal. Now I see why everybody says shooting the 10mm is so much fun. all I can say is WOW!! :eek: