Don't carry either for EDC, but would like to have a holster for them. On Glock USA website I did a compare of a G21 Gen4 and a G17 Gen5, the 2 guns I own. I see the width on both of them is 34mm (1.34"), and the barrel length and overall length of the 2 only differ by 3mm. Height is only 1mm different.

Thinking this one holster might handle both guns. Anybody see a problem with my logic?

Trying not to add 2 more holsters to the drawer full that will barely close now.

I don't expect the 21 will fit in an Avenger for the 17. Thinking you'll have to start with one for the 21.

Then, I believe the 17 will be a sloppy fit.

Oops, Galco doesn't show an Avenger for a 21.

Like your plan though, holsters do have a way of piling up.

The Glock 21 and Glock 20 models are a larger Frame . Slide is wider


Glock 21: length of slide 7.59 inches, width 1.27 inches

Glock 17: length of slide 7.32 inches, width 1.18 inches

I can't speak to Galco, but my Bianchi for a 17 won't fit my 20.