Shot my g19 4th gen today with the spring conversion kit. This enables the 4th gen glock to use a 3rd gen spring. Before, i was not able to consecutively fire 2 shots without a jam. Today, i only had jams when testing the 4th gen spring. With the spring kit in, i had 0 jams. I shot about 200 rounds with the new kit in and did not have any problems. If you have problems with your g19 spring i would highly recommend this! Tried all different types of ammo. 115grain Remington umc ran flawlessly, and we all know how terrible that stuff is. I also got some trijicon sights installed this morning and they are wonderful. I shot with 2 co workers who also have g19s (3rd gen and 3rd gen rtf) and they actually preferred the feel of the 4th gen's frame. I will be going again this week to shoot a few hundred more rounds but this spring conversion kit is wonderful! I got it on glockparts.com for about 23$ with shipping. I ordered it Thursday morning and received it Saturday. It was shipped from Colorado and i live in Virginia so that sight is very fast. Also, i have the 4th gen 04 spring on the way from glock so hopefully this week ill be able to report how that spring goes. I had an 03.