Was wondering what you are using for brass. I broke down and bought some properly head stamped brass which was pretty pricey but I also have some 500 S&W brass that I am going to cut down. I saw something on one of the sites about turning the heads down for use in the FA revolvers, is that also required for the BFR? Also, if anyone has a min/max recipe using Win296/H110 for the BearTooth 440's that would be great as well. Thanks as always for any info you can provide.
The original spec for the .500 JRH has a smaller rim than the .500 S&W. It was designed for the limited confines of the FA83 originally and hence the smaller rim. The BFR was cut for the bigger rim of the .500 Smith & Wesson so it will not be a problem using standard S&W rims.
I use properly headstamped brass myself. I have gotten the best accuracy from top-end 296 loads myself. My BFRs prefer the top-end loads. My go-to (safe in my guns, may not be in yours - my disclaimer) is 29.5 grains of 296 under a 440 grain cast bullet (Cast Performance) and the same load under a 420 grain Kodiak Punch bullet. Rimrock makes a great 440 that is worth considering.