Bulldog,

My Searcy .500 was regulated with Woodleigh 570 gr. softs over 110 grains IMR4831.

I have also gotten it to regulate perfectly with the following:

110 gr. IMR 4831 570 grain Woodleigh solids
110 gr. IMR 4831 550 grain Bridger solids
106 gr. IMR 4831 570 grain GS Custom FN solids
103 gr. H4350 570 grain GS Custom FN solids
103 gr. H4350 550 grain Bridger solids
103 gr. H4350 570 grain Woodleigh solids
103 gr. H4350 570 grain Woodleigh softs
96 gr. Re 15 570 grain Woodleigh soft with Kynoch filler (have not really messed with the other bullets using this load)
45.0 gr. XMP5744 500 grain cast lead.

So overall that rifle is not too picky at all.

I suggest having Butch regulate your .500 with 110 grains IMR4831 and 570 grain Woodleigh solids. From there I am sure you can get FN solids to regulate if you want. But I would not go with a non-standard regulation as it could make you rifle hard to sell should you ever choose to part with it.