All 105-107 gr bullets I've shot in different 243win's have always liked H-4831 / H-4831sc. 40 to 43.5 gr does the job. COAL can make the difference on what powder charge is best.
At 2.800" to 2.850" COAL 42 to 43.5 gr H-4831 always worked for me.
Shorter COAL means less powder needed to generate same pressure.