What came first, the chicken or the egg?
The Glock 20 or the 21?
The first Glock 20's have serial prefix 'MC' and were made in July 1990.
The first Glock 21's have serial prefix 'UB' and were made in December 1990.
They were designed concurrently, with the 10mm taking the lead and .45 being a derivative.
It's apparent in a couple places, but the two key points are the slide having material removed to make it lighter because of the reduced recoil impulse of .45 and the frame having a second pin to better hold the locking block which is unneeded for .45. This second pin shows up on Gen3 Glocks as well because .40 S&W was stressing the small frames the same way 10mm stressed the large frames.
In most places, both hit the shelves at the same time.
The Glock 20 or the 21?
The first Glock 20's have serial prefix 'MC' and were made in July 1990.
The first Glock 21's have serial prefix 'UB' and were made in December 1990.
They were designed concurrently, with the 10mm taking the lead and .45 being a derivative.
It's apparent in a couple places, but the two key points are the slide having material removed to make it lighter because of the reduced recoil impulse of .45 and the frame having a second pin to better hold the locking block which is unneeded for .45. This second pin shows up on Gen3 Glocks as well because .40 S&W was stressing the small frames the same way 10mm stressed the large frames.
In most places, both hit the shelves at the same time.