Assuming it isn't just weak ammo, perhaps look for a polymer rub on the slide. I had this happen on a P-09, I think. Remove the slide and take the guide rod/spring out and then put the slide back on the frame and move it to the rear and see if you can feel any roughness. You may have to turn the gun upside down to get the barrel to go back in to battery without the spring in place. Or just remove the barrel. You will have to pull the trigger to get the slide back off with the barrel and/or spring removed. Trim away any polymer rubs or file off any burrs on the frame insert.
Joe