My Colt Delta Elite from 1987 has fired nothing but full house 10mm...mostly PROLOAD Factory ammo. I have never had any parts failure but I do use a 22# spring.
10mm is awesome....I have taken Antelope in Wyoming at 100 yards with a one shot kill to the neck. Had a guy sighting his rifle in at 100 yards bet I couldn't hit a man sized target at 100 yards....that cost him $ 100...all 9 rounds hit the target in the torso ! 10mm drops less that 3 inches at 100 yards.
Too bad PROLOAD went out of the ammo business...they were the first US manufacture to make full house 10mm that matched Norma velocity and was much more accurate.
You should know while the Glock 21 is very shootable, the barrel is not heat treated. Put a Lonewolff barrel in it and enjoy a heat treated barrel with more case head support.
10mm has performed well. FBI agents didn't like it as too heavy in the S&W pistol and 10mm carriers were required to carry a minimum of 3 spare magzines.