GLOCK, Gmbh, Austria introduced a variation of its G21 in .45ACP, the G21 SF (Short Frame) at the 2007 Sporting, Hunting and Outdoor Trade (SHOT) Show. The newest version’s designation follows GLOCK’s logical system of indicating changes to the original model as illustrated by the G17 with a longer slide and barrel installed becoming the G17L. For GLOCK aficionados, the company deviated from this with the G34 and G35, which are the G17 (9mm) and G22 (.40), respectively, with longer slides and barrels, and extended slide catch and magazine release. For that matter, these are also the first to be given a grammatical label, Practical/Tactical. So with the G21 SF, GLOCK continues its logical numbering system.
First, let’s look at the modifications made. These changes are slight by comparison to the others mentioned above, but the accumulation warrants a stand-alone identity. Starting up front, the dust cover accessory rail now has a second option, a Picatinny-style rail, along with the original GLOCK rail, which is also referred to as a Universal rail, based on Weaver scope mount dimensions. The slide is slightly shorter, going from 8.23 inches to 8.11 inches, in my opinion, to allow for the use of optional barrels such as would be used for the United States Special Operations Command (USSOCOM) required adaptability for a sound suppressor.