Finally made it to the range today to test out my new underwood carry ammo. I got the 200gr. xtp. Wanted to make sure they would cycle properly like any intelligent person should. 1st of let me say, WOW. This ammo feels awesome to shoot. Haven't had that much fun since shooting my friends S&W 500. The cases seem to eject a mile. It was close to dusk so the bugs where terrible. The mosquitoes have been bad since all the rain we got this spring. Lastly, I was very disappointed as my 20sf didn't seem to cycle very well. I have a 22lb recoil spring. I only fired 18 rounds and picked up brass before I had to get out of there, but I had 8-10 failure to feeds. I just bought this gun a short time ago. I'm going to go back out tomorrow and try some more with the stock RSA. We shall see if it was that or a magazine issue. 2 of the F2Fs left rounds standing straight up in the mag. It is a 3rd gen 20sf for those who are wondering. It also happened mostly in the middle of the magazine. First 3-4 rounds cycled fine and the last 3-4 cycled fine.