I know it’s easy to convert a g33 to 9mm. Is it possible to convert a gen 4 g26 to .357? FWIW I can just get a gen 4 33 for $410 so I’m only interested in options that would be less than that.

i think you need a different slide/upper that can handle the higher pressures..   IIRC - the oem 9mm barrels are smaller in diameter than the 357 etc - so the bigger calibers wont fit in a 9mm upper/slide

357/40 barrels don't fit in 9mm slides.

If you have a Glock 27 40 caliber you just swap barrels as a 357 Sig cartridge is a necked down 40.   The breach face of the Glock 26 probably won’t accommodate the larger 40/357 Sig case head.   If you have a Glock 27 you can get a 9 MM conversion barrel or use a Glock factory 357 Sig barrel and get 3 calibers in one gun.  Add an Advantage Arms 22 conversion and you have a four caliber Glock 27.  The only difference in a Glock 27 and Glock 26 frame is the ejector which is easy and inexpensive to change.   I’ve read the 357 Sig cartridges feed out of Glock 27 mags but I’ve never tried.   If you put a 9 MM conversion barrel in a Glock 27 your better off using 9 MM mags.

I figured this was the answer. Looks like I should have gone with a 27 or 33.

Thanks for the responses.

Go downward in caliber, not upward.

You'd need a complete G33 top end + different ejector in Trigger Housing to do it.  Almost a whole other gun.

I'd just buy the G33.