The 124 gr Match Winner is a great bullet. Yes they can be an issue with some weapons. Every gun is different. You must find the right seating depth for gun. We all heard that a million times! One of the things I tried, and was successful, after I found the PERFICT OAL, was to switch to a
Lee Carbide taper crimp die. It will iron out any bulges, or out of roundness or distortions in the brass. It actually burnishes the brass to a nice shine. It also makes a perfect crimp, and is very fine adjustable. I now use a Lee seat die on ALL my .45acp loads also.
Sometimes with the profile of the MW running up the feed ramp, it is possible to feel a slight bump. Also when that happens, if you measure the OAL, you may find a slight set back. This may slow the final chambering process, cause an insufficient lock up or even misfire.
I compared 124 Match winners vs 124 RMR FMJs, many times. I use my most accurate competition gun with a Leopold Red dot on sand bags. I find NO difference in accuracy. Over the Chronograph I do find the MWs slightly more consistent, but at normal shooting distance ( 3-25yds) no effect on group size.
On defense of the MWs, they make cleaner holes it cardboard and paper targets. With my 72 year old eyes, that is a big deal shooting IDPA competition. I am slow, and I suck, I can use every edge I can get.