Glock pistols have changed in the last few years, which is why it's interesting to look at two of the newest Glock models—the G21C Gen 3 and the G21 Gen 4—and examine their advantages and disadvantages.
Glock's G21 Gen 4 Pistol in Pictures
The G21C and G21 Gen 4 are nearly identical except for their specific features. Gen 4 has a captive dual recoil spring and interchangeable backstraps. The G21C is compensated.
Both the G21C (top) and G21 Gen 4 are designed to shoot softer than standard .45 ACP Glock pistols.
The G21 Gen 4 features interchangeable backstraps to allow the shooter to fit the pistol to his or her hand.