I figured that since my tax money is buying so much 40 S&W ammo that it would be a good idea to be able to use some of it with this conversion barrel. Plus shooting 40 instead of 10mm will cut down on the cost of target practice. I started out shooting my target practice reloads and then 4 other brands of ammo for my test. 150 rounds total were fired. All loads functioned perfect and the accuracy was the same as shooting 10mm at 25 yards. Below is the ammo I used: Reloads - 165gr FMJ FP (Flat Point) Wolf Steel Case - 180gr FMJ FP Blazer Aluminum Case - 180gr FMJ FP Corbon - 165gr JHP Double Tap - 180gr JHP I also have a G29 conversion barrel on backorder and hope it works as well as this one does. Will add to this post when I try it out. Update 2/25/13: I finally received my G29 barrel that has been on back order since the middle of October (4 months). I ran the same test as above using the same ammo. There were no problems and the accuracy was the same as the stock barrel. I would recommend both of these to anyone that owns a G20 and/or G29 for the versatility if 10mm becomes unavailable.