[wildcatP11]

I have a new P11 with about 100 rounds through it so far. I get an FTF when the mag has 9 or more rounds in it. In other words, I pack ten into the mag, rack the slide (leaving 9 in the mag), fire, it jams feeding the next round...every time. If I do the same with one less round in the mag, it works perfectly. What is the deal? This is using Winchester 50 round white box 115gr FMJ, which feeds perfectly in any other situation. I only have one mag, so I have not tried it with another one.

Anyone tried the Federal Expanding FMJ?

 

[Flyer]

My guess is that a good fluff & buff will do the job...
Your slide isn't coming forward with enough force to strip the top round of a loaded mag, the only one under full tension: smoothing the feed ramp, hammer interface, and inside of slide rails will decrease friction and allow the slide to fully seat, chambering the round.
Also, you might want to try a stronger recoil spring.
I'd say, though, polishing the feed ramp and hammer interface will likely cure the problem.
Flyer

 

[wildcatP11]

OK, thanks, I'll do that. I did a F&B on the trigger bar, but not the slide, though I did lightly grease it. I think I am going to try the magazine lip bend too. The rounds seem to have little or no upward tilt to them. When it jams, if I drop the clip out of the gun, the jammed round is still in it.

BTW, I ordered some 124gr Federal EFMJ's today. I'll let you know how they feed and shoot after I try them out.