No nibbles probably because giving out load data that you have proven to be safe in your firearm is foolhardy since it doesn't automatically equate to it being safe in another person's firearm. I don't pass mine along for both that reason and because I don't know the reloading practices or skill of someone else.
I never owned any 375JDJ carbine/rifle barrels, but did have four 14" SSK barrels. My bullet weights of choice where 270, 285 and 300 grain for them though, with the 270 Hornady SP shot the most by a large margin. Shot a few 220 gr trying them out, but went back to the heavier bullets. Took plenty of game with them from small to large to dangerous. Best advise for a so called pet load is to simply follow JD's data sheets and seating suggestions yourself to find what safe load your particular barrel likes with your bullet choice for that loads intended purpose.
I agree with Chris that JD is a fan of the 270's in the 375JDJ, although in the early years of the 375JDJ's he used 300 gr solids and 300 gr. Hornady FMJ's for shooting elephant and cape buffs; the 375JDJ and 45-70 for the larger plains game and the 6.5JDJ for other plains game.
L.