I haven't tried it on my Glock 32 (same size as your 19), but I have the TLR-1 C4 on my duty weapon (Glock 31). I have had versions of the TLR-1 since the halogen bulb days, then the LED, and now the C4 LED.
Amazing light. It has worked fine on my Glock 31 (and Glock 22) before that. I tighten it down with a nickel. No need to crank it on like there is no tomorrow. I've never had it come off (so far I've gotten a few thousand rounds through my gen3 31 and now it is on my gen4 31 with over 1000 rounds). This thing is tough and Streamlight's warranty is hard to beat. I have not had to use the warranty yet on any of my LED models. I killed a halogen model years ago by using too powerful a battery (3.7V instead of the required 3.0V) and Streamlight replaced it.
The TLR-1 is kind of big on the 31, so it will be big on your 19. It fits the Glocks just fine and I can reach it with my trigger finger for activation. I have a TLR-3 on my FNS-9. I will find the key for Glock and put it on my 32 so you can see a picture of the TLR-3. (My TLR-1 is at work and I am not back to work till Friday).
Will try to get a picture tonight or tomorrow for you.
Of course the TLR-1 is brighter and has easier to obtain batteries (CR123). The TLR-1 uses two CR123 batteries (can be had for about $1 each if you buy in bulk). The TLR-3 uses a CR2 battery. Costs just a little more.
Both are fine lights.
I had the TLR-3 on my AR15 and it withstood full auto firing, so on my puny handgun, it should be ok.
here, for now i have some old pics on imageshack already.
FNS-9 with TLR-3
Glock 31 (gen3) with TLR-1
lucky for you, I found an old pic I did. Glock 32 with TLR-1 (ignore the Glock 31 with cheap SIG lite)
http://imageshack.us/a/img577/6619/23363812.jpg
HK P2000 with TLR-1
http://imageshack.us/a/img142/7701/p2000biu6.jpg
PSA AR15 with TLR-3
http://imageshack.us/a/img72/1079/dsc01978sm.jpg
Hope that helps.
the third picture is the one you really want with the Glock 32 with TLR-1.
Your images are too large and have been replaced with links Please resize and repost.
See Rule #3 If you post an image in your post, please downsize the image to no larger than 800 x 800 pixels. - Thanks Norm