Nope. You can get a 357SIG and .40S&W aftermarket barrel for it. But why? $9.50 for a box of 50 FMJ is a darn good price for ammo, regardless. You can get a 45ACP Glock 21 slide assembly/mag for it. Heres the barrel compatibility list:
Barrel ------------Gun/s
G17.....................G17
G17L...................G17,17L,34
G19.....................G19,26
G20.....................G20
G21.....................G21
G22.....................G22,31
G23.....................G23,27,32,33
G24.....................G22,24,31,35
G26.....................G26
G27.....................G27,G33
G29.....................G29
G30.....................G30
G31.....................G22,31
G32.....................G23,27,32,33
G33.....................G27,33
G34.....................G17,34
G35.....................G22,31,35
Here's the slide/frame compatibility list:
* Indicates ejector and mag change.
Receiver------------Upper/s
G17.....................G17,17L,34
G17L...................G17,17L,34
G19.....................G19
G20.....................G20,G21
G21.....................G20,21
G22.....................G17*,17L*,22,24,31,34*,35
G23.....................G19*,23,32
G24.....................G17*,17L*,22,24,31,34*,35
G26.....................G26,27*,33*
G27.....................G26*,27,33
G29.....................G29,30*
G30.....................G29*,G30
G31.....................G17*,17L*,22,24,31,34*,35
G32.....................G19*,23,32
G33.....................G26*,27,33
G34.....................G17,17L,34
G35.....................G17*,17L*,22,24,31,34*,35
These lists were taken from Glockmeister's awesome website:
http://www.glockmeister.com/