I went to the NRA range today and bought a (white) box of Winchester (black lettering)
9mm NATO (124 grain FMJ)
The recoil was harder and every 1-2 rounds the Luger jammed. I tried several rounds and then gave up.

Then I switched back to my regular Winchester White Box ammo with 115 grain bullets and the gun shot smooth and flawless like always.

I shot Magtech, Remington UMS, American Eagle and never experienced this before. (They all had 115grain bullets).
I didn't know that a 124 grain bullet makes such a big difference.
Is a 124 grain bullet just too heavy for a Luger?