USMC66, I have the 9MM conversion barrel for my Glock 22 and it works about 95% when I put in the barrel and use FACTORY Glock 9MM magazines. Every now and then I get a FTE. The reason for this is that the extractor for the .40 doesn't reach in far enough to grab the smaller 9MM shell and the ejector is not angled in far enough to kick out the shell, so it's working off of blow back only to eject, which works for the most part, but is not 100% reliable. If you aren't using the 9MM conversion for self defense it will most likely be fine for the range as long as you expect the occasional stove pipe or failure to eject. The simple fix provided you have some basic knowledge of Glock disassembly and reassembly is as follows if you are going to want the gun to operate with factory reliability: 1) Buy and install the 9mm loaded spring bearing ($3) and the 9MM extractor ($20) and install in place of the .40 parts in your slide. 2) Buy and install the 9MM trigger mechanism housing w/ejector ($10) and install in the place of the .40 cal part in your lower. 3) Buy a Glock FACTORY 9MM magazine ($30). Once you make these changes in addition to the conversion barrel you Glock 22 will function as a true Glock 17 9MM. The total conversion to 9MM or back to .40 takes 10-15 minutes if you know what you are doing. I did mine this way for just for versatility and have had 100% reliability since. I only use the conversion occasionally, but at least I have options.