My experience has been that any of the extruded tubular powders, 4198, RL7, 3031, 4895, 4064, RL15, Varget all respond positively to the 70% of full charge reduced load approximation suggested for 4895.
with 4198 and RL7 specifically, I have no issues using 50% of case capacity.
My experiments with MP5744 years ago were erratic. and I have no current experience with that powder and don't recommend it. Similar experiments with other Accurate rifle powders resulted in their being put on the lawn as fertilizer. I use only Alliant, IMR (either Expro-Canada or Mulwex-Australia) product or Norma, Vitavouri, Nobel-Sport extruded tubular.
I DON'T attempt reducing charges with slower powders such as 4350, 4831, etc. nor do I with ANY coated Ball or spheroidal powder. Doing so is a No-No with H110, W296, W680, A1680, A2230, H335, H380, WC844/846, Ball C2, W748/760, etc. I don't experiment beyond published loads with ANY Ball rifle powders.
UNCOATED, rolled flake Ball powders such as WST, WSF, 231, act "more like" flake shotgun or pistol powders and offer possibilities for the careful and knowledgeable reloader, but aren't for the novice to play with outside the box.
I confess that I do almost no match shooting anymore. I mostly enjoy single-action revolvers, milsurps and lever-action cowboy rifles. If I can stay on a 12" steel gong at 200 yards with iron sights with a milsurp or lever rifle or 100 yards with a fixed sight revolver I consider it a "good" load. When load testing I shoot only ten-shot groups. If I can shoot a 1 mil ten-shot group with iron sights, and the group is round, circular-normal with good center density, that is as good as they shot buffalo and killed Indians with.
My best loads do better, I would hope so, but people get too wrapped around the axle looking for levels of benchrest accuracy which are unnecessary except for competition and mental masturbation.
73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia