Josh
Every R9 is different. My first one was not reliable with anything but Bazer aluminum. I never use that stuff but I was desperate. I tried 115's, 124's, and 147,s. Nothing worked.
The second R9 I have will work with any ammunition I have tried. 115's, 124's, and 147's all work. I have not had one single failure with it. I have only used premium self defense type ammo though. No cheap FMJ's.
Part of the R9's ammo problems in my opinion is the extremely light weight slide. All other manufacturers rely partially on slide weight to help the gun function. Springs are not as reliable as good old mass to delay the slide opening.
JMO
P.S. Both the Solo's I have owned will work fine with 115 grain ammunitition in contrast to the company recommendations.
Again, only premium self defense type ammo which is loaded hotter.