Glock G21 Gen5 MOS .45 ACP vs HK HK45 .45 ACP

Both are polymer-framed full-size .45 ACP pistols within 0.04" of each other in overall length (8.07" vs 8.03"). The Glock G21 Gen5 MOS .45 ACP carries three more rounds at 13+1 against 10+1, weighs 2.1 oz less (29.1 oz vs 31.2 oz), is narrower at 1.38" against 1.54", and is optic-ready where the HK HK45 .45 ACP is not. The HK45 is DA/SA with a manual safety and decocker and a listed 4.5 lb trigger, 1.3 lb lighter than the G21's 5.8 lb striker pull. MSRP is $700.00 against $949.00, a $249.00 gap.

Pick the Glock G21 Gen5 MOS if:

• Capacity matters: 13+1 against 10+1, three more rounds of .45
• You want a red dot without slide work; the MOS is optic-ready and the HK45 is not
• You want the lighter, narrower gun at $249.00 less: 29.1 oz and 1.38" against 31.2 oz and 1.54", with three magazines instead of two

Pick the HK HK45 if:

• You want a DA/SA hammer gun with a manual safety and decocker rather than a striker with a trigger safety
• The 4.5 lb single-action trigger matters more than the 5.8 lb striker pull
• The taller 5.91" grip and interchangeable backstraps fit your hand better than the G21 frame

The G21 wins on the countable specs — three more rounds, 2.1 oz lighter, narrower, optic-ready and $249.00 cheaper. The HK45 is the pick if you specifically want DA/SA controls and its lighter listed trigger.