SF = Short Frame. It's "shorter" from front to back. They reduced the "hump" (anyone can heat up the back of their Glock grip and simply push it in to do this...).
For you whiny sissy-boys that complain about a dang hump on a grip "feeling uncomfortable" (wah waaaaaah!
): It's there for a reason. There's a hole on the bottom so you can slip your finger inside to more effectively grasp the magazine in case it jams one day. This was put on Glocks because the [Austrian] soldiers wanted this when Gaston was designing this pistol. So, you see, there's a TACTICAL reason for the "hump" back there. It's not for girly-men who whine about how "it feels" all the time. You'll thank the heavens it's there if your mag ever jams in combat. Enough said.
BTW: The Glock 21 (and 21SF) holds 14* rounds in it! Thirteen in the magazine, one in the chamber! Just to clarify.
GLOCK has come out with the Glock 30SF, as well; for those who want a compact sized SF model in .45 ACP. I
believe they're coming out with SF models for all other calibers, as well. But, we'll have to wait and see.
Remember, you can easily heat up the back up your TOTALLY UNLOADED pistol grip and push it in to reduce the hump, if it annoys you that much.
The angle simply takes getting used to, is all. There're people that say Glock feels awkward to them, yet they shoot the Glock better than their other gun without a slant on it, for "some odd reason."
The SF is NOT the "Slim frame." The only Slim framed Glock is the Glock 36. This model is thinner from side to side, as in how thick the gun is, not front to back. It's 1.1 inches thick.
Glocks have thicker grips because they usually hold more rounds than most other guns, and usually in double-stack style.
Now that I educated you guys, maybe you'll give Glock more of a chance, seeing as how there're good [tactical] reasons as to
why Glock grips are... the way they are. RESPECT THEM! They deserve it! :banghead: