If you bullet is getting knocked around as it hits the feed ramp something is mighty wrong. If there is that little bullet left in the case then you are using the wrong bullet or loading way too long. Infinity recommends that in their 40, (aet barrel) you load 1.210, that is longer than most 40 which load 1.135 - 1.180. I will ask them why so long next time I have an opportunity to speak with them. I used 1.210 OAL (200gr blue bullet,vitn320) in a friends STI and they shot very accurate and fed without jamming. As someone suggested, EVERY GUN/BARREL is different, you have to test for yourself.