Just got back from running the 80g GMX in my Savage M10 .243, 22" sporter bbl.
All over the chrony @ 15', 100 yard groups.
Not one single issue with pressure, all primers nicely rounded & could go at least 2g more IMO,
3200 fps is good for me to 600 yards out here.
80g gmx, cci200, 44g w760, 2.750" col, 3231 fps .600"
44g 2700, 3218 fps, .900"
40g imr3420, 3210fps, .850"
41g h380, 3137fps, .980"
38g xbr8208, 3193fps, 1.300"
I ran 5 shots w/my 65g coyote load then ran all the 80g GMX loads, no barrel cleaning. Pulled the bolt after each 5 rounds and the barrel was clean w/no dirty powder residue left behind with any of those I used.