I finally shot my R9S serial # R68#. I shot 260 rounds over 3 different sessions.
1st day: 72 rounds of Gold dot 124 gr standard pressure. With a very strong 2 handed hold I would get a Failure to Feed on the 5th round of both magazines almost every time. With a strong one handed hold I would get random FTFs. They were all the same. It looked like the round wanted to chamber but would get stuck at an angle.
Safety Warning: I had 3 strange occurences. The hammer would get stuck to the rear as if it was "cocked" like a single action. I tried to press the trigger again but it didn't help. The fist two times I simply unloaded the gun and racked the slide to reset the hammer. My luck ran out the third time. As I disengaged the mag catch, the hammer dropped, causing the gun to discharge. Since I did not have a firing grip, I ended up dropping the gun. My hand stung painfully and for a horrified instant I thought that I had shot myself. Fortunately the gun dropped onto a rubber mat, the round went downrange, and I was uninjured. That shook me up and I stopped for the day.
Although this is my first Rohrbaugh, I'm fairly experienced with other guns. I'm a longtime police department firearms instructor and rangemaster. I have been to numerous armorer courses and I worked as an armorer during my Marine Corps service many years ago. I figured that I probably had a burr or sharp edge somewhere in the internals. I hoped that it would smooth out with further shooting and it seems I was right.
2nd day: I cleaned and relubed with superlube per the instructions contained elsewhere on this site. I could not punch the pin out with hand pressure alone. I found that the thin end of a military cleaning toothbrush wedged between the breechface and barrel hood holds the slide open perfectly so that the pin could be tapped out. I shot the remainder of my gold dots (28 rounds) I had the half cock problem once and then it went away for good. Again I noticed FTF's on the 5th round of both mags every time.
When I finished with my Gold Dots, I started shooting 115 grain Silvertips and had much better results. I only had half a box full but out of 4 mags I only had one FTF (5th round of course). The Silvertips were much softer shooting than the Gold Dots but had way more muzzle flash. I may experiment more with them in the future. Strangely, the gun also felt smoother.
I also shot some old 147 grain Hydra-Shoks. Again I only had half a box but out of 4 mags I only had one FTF (5th round). Muzzle flash is non existent with this round.
I began to obsess on the 5th round problem. That night while cleaning the gun, I disassembled and examined the magazines. I noticed that there was roughly welded area on the inside of the back of the magazines. Using just a wooden handled Q-tip and Flitz polish, I lightly polished the rough area. I also thoroughly cleaned the magazines. The polishing seemed to help.
3rd day: I shot 50 rounds of the 147 gr Hydra shok and 50 rounds of 147 gr Ranger SXT. With a strong two handed hold I got no malfunctions at all with one magazine. The other mag would still FTF on the 5th round almost every time. I even got two complete mags in a row with no malfunctions shooting one handed.
100 rounds in one session is a lot with this gun. I am going to change recoil springs and polish that other mag a little more. Does anyone have any suggestions about that 5th round thing?