Fairly close.

G23 gen 5 slide width is .08" wider (for possible holster considerations).

Other stats:
GLOCK Inc. | GLOCK Pistols | Buy Guns Online (G23 gen5)

GLOCK Inc. | GLOCK Pistols | Buy Guns Online (G19 gen5)

 

Thank you. I have a Gen 3 G23, but I don't have a 19 or 17 handy to compare them...

 

The gen 5 23 is wider on the slide width.

 

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Here are some pictures:

G45.5+G23.5= G23X? A GLOCK Modular Comparison

Today, I got to shoot a few new guns. Of those, two were ripe for an experiment. I brought out the G45.5 and the recently released G23.5. I have read discussion of putting the G23.5 slide on the G45.5 frame, which would give a person a .40 S&W the size of a G19X. So, I decided to make and...

www.glocktalk.com

 

My Glock 23 is my Glock 19. I just change out the barrel and magazine.

 

I agree with Darkangel.....G23 with a 9mm barrel, works very well.