After playing with and testing as many different bullets as I could beg, borrow, and purchase, I ended up ( very successfully) using 260 grain 375 Accubonds ( also 260 grain ballistic tips) in the G2 Contender in 378GNR. They patterned by far the best, and they both hit same point of aim.
In the FA83, which I mostly used this trip, my normal accuracy load, but with 300 grain Swift Hollow Points performed flawlessly. They were just as accurate as the 300 grain Hornady XTP’s I tested, but everything I shot the Swifts into from water jugs, to a gravel pile, the recovered bullets looked like a magazine ad. Perfect mushroom. Took 6 critters total, 4 revolver, two, at longer ranges with the single shot contender.