I started loading for my 308 Ar 10 24 inch barrel and my 300 ultra semi custom SPS , I started loading the 308 using serria load data chose 168 match king reloader 15 , worked up to 43.4 with .68 groups at 100 yards , my chrono was giving me Ava @2760 , I have shot federal box ammo match kings 168 thru the chrono speed 2720 with groups closer to .50 ,these are 5 shot groups , my question is I am 1/10 grain over max no presser signs , another loader I know says loads in most books are for bolt guns , and I might be pushing my AR to early bolt problems , my questions are any loaders loading from bullet manuals how close are they to max loads ? Also tried 178 amax with AR Comp powder getting right @ 2590 with 37.5 grains 3/4 groups at 100 went up to 39 gr starting load had the best group but my speeds where all over the place might be my chrono, Then there is my 300 ultra , this gun has given me head aches , started,loading 185 Berger VDLS OAL 360 loaded 94 gr retumbo chrono have me 3220 all under and inch , went up to 96.5 best group was the 94 grains , best group was shot in the morning in Houston tx , shot them same loads Friday , velocity where good they where all within 15-20 FPS but gun would not group , was this due to temperature 20 deg difference ? This gun has shot well but now has about 500-600 rounds thru it regular contour barrel gets hot quick , I let it cool between shots , not sure what going on or I might just be me , I just thought I would be harder to get the gas gun to shoot good just starting to reloading and the bolt would be easier ? Just getting frustrated with my 300 ultra and suggestions would be greatfull 308 using max load out of manuals ? 300 ultra what to do next ?