For this test I sorted once fired Lapua brass in .223 with less than .0005 runout at neck and distributed 5 cases with the same runout between the 2 presses, body sized with Redding die then neck sized with LCD and finally seated with Forster die. First thing I noticed was Mec varied shoulder bump around .001, rebel was right on for 4 cases and off by .005 on one case, next I found that if you pressed on the arm harder with the mec press my bullet seating length could be off by .004 depending on how hard you push, with the rebel the seating length stayed the same if you pushed on it harder so this explains why shoulder bump varied much more on mec. Lastly I measured runout at ogive, mec averaged .00115 with worst runout at .002 and best at .00025, rebel averaged .00089 with worst at .00125 and best at .0005. What I think kinda matters most from this test is that the mec could give various results on shoulder bump and seating depending on your force working the press, if you have a shoulder gauge this can be checked but of course you can't make it grow if you push shoulder to far and seating can be checked also but will involve more tinkering, if you don't have shoulder gauge try and keep your pressure the same. In the end the runout was a little better with rebel but I think where it shines is that it is more consistent with a solid dead stop, using the rebel was less tidious cause results were very predictable, this MEC press might be going back, lol.