Yes, you can buy a Glock factory .357 barrel made for the Glock 33 and drop it into a G27 to get a .357 option.
Originally Posted by hrk
You can't do that with a Glock factory 9mm (G26) barrel, because the width of the barrel is different at the rear, near the breechface. But, you can get a specially made aftermarket barrel made by another company to drop in and shoot 9mm in a .40-sized gun. You'd probably need 9mm magazines for this set-up to shoot reliably.
Unless you want the ambidextrous magazine release, or the frame of a Gen3 G26/G27/G33 is a tiny bit too large for your hand, the Gen4 subcompact guns offer no real advantage over the Gen3 guns. All the Gen3 subcompacts already have the dual-coil recoil spring; they've always had it, right from the day they were introduced.
jakeleinen1, the G30 is larger than the G26/27/33 guns; it's approximately the same height and length as a G19/G23/G32, but thicker. It's considered a subcompact in the large-frame (.45 ACP and 10mm) lineup, but it's considerably larger than the small-frame subcompacts. If a person wants a .45 caliber bullet in a G26/G27/G33 size package, the closest you can get is the G39 in .45 GAP caliber, and even then, the slide is slightly thicker.
"Placement is power" -- seen in an article by Stephen A. Camp
(RIP, Mr. Camp; you will be remembered, and missed)