Reloader 26 and 243 Win with 100 grain bullets

Alliant is listing 47.9gr as max with the 100gr Sierra GameKings.
47.1gr max with the Partition.

I had gotten my wife a Rossi R243 back some years ago. For being so inexpensive, it was surprisingly accurate.
I was reloading the 100gr GameKings over RL26 for it.
Friend gave me a box of 100gr Rem Corelokts.
When comparing them, the Corelokts shot 8" lower & about 6" to the right at 100 yards.

Been working with 243 loads here and IMR7828sc, Rem 9 1/2 primers resulting in average MVs of 2950 with Sierra 100gr pills

So far Superformance behind Hornady's 103 grain ELDX seems to hold more promise than anything. I'm limited on seating depth as .020 under won't fit in my magazine. It's still early, but the last three were about a dime sized group with 44 grains of powder. Pressure at 45, so I can't go up much from there. 3060fps by LabRadar. Close to 3200 fps with RL 26 and no pressure, but 1-1/4" was the best I could get for accuracy, some much worse. One flyer out of around 30 rounds was 4" higher and another 3" left, and it wasn't me. I'm the first to admit there's plenty of better shooters, but I was bagged in, stable bench, triggertech diamond trigger and a good squeeze on all. My gun with where I can seat my bullets just ain't gonna shoot what I have with RL 26.

Update on my new load findings
108 berger elite hunter
H4831sc
Sig brass
Federal 210
Gives me 3232 fps and great accuracy