9mm conversion

Yup. You can take up extra space on the 40/9 with a thicker barrel. But you can't go the other way.

My main question to you is Why would you want to convert it to shoot 40S&W? After doing our little 9x19mm+P vs 45acp Ballistic Jell test(in the Ammo and Reloading section) I'm totally convinced that ANY major caliber handgun round will be equally as effective if you 1)Use quality HP defensive ammo and 2)Place your shots on target where they'll do the most damage. SO, it seems like instead of a conversion barrel what you really need is some high quality ammo like Gold Dot, XTP or Golden Sabers sitting in your G19c, not a new barrel in 40S&W.
And before someone says it, YES, I do LOVE my G30 in 45acp but I'd still not feel undergunned if I had to have a G19 in 9x19mm as long as I had good quality ammo in it. As always, JMHO, YMMV.

You can't do a "Barrel" conversion in your 19.

You could, conceivably drop on a FULL G23 slide since the lowers are the same size. You'd also need new mags.

There are other models that can take a conversion barrel.

Generally you cannot go UP in caliber.

TNFrank is right though, most modern defense ammo, in 9mm is sufficient.

D

Probably need a new trigger group for the G23 slide, but definitely a different ejector.

Thanks for all the replies.
I have looked at the cost of using a 40 vs a 9, and that's one reason for the 9. I like going and shooting at least 100 rnds, at least once a month. So as far as expense, the 9 is the way to go. I just felt like I was mis informed about the conversion when I bought my 9. I'm perfectly happy with my 9, I have nothing bad that I can say about it, except that I can't go out and shoot enough.
For CCW, I'm sticking with the 9mm anyway, but was also considering a 40 for home defense. But that's a later topic.