My .500 A2 will approach 2500 fps with 600 grain bullets, so I'd think the larger Gibbs cartridge will do something over 2600 fps with the right load. In my view, there is a very different experience shooting the 570 or 600 grain bullets at 2250 fps and at 2450 fps. That extra 200 fps adds a sharp edge to the existing very significant recoil. Since a solid pushed to 2250 fps from a .50 caliber rifle will kill any elephant on Earth from any reasonable angle, I think the only application where more velocity might be helpful is with soft points on cape buffalo, etc. Bear in mind that the Woodleigh bullets are designed for the classic .500 NE and .505 Gibbs loads at the standard factory velocity. Pushing those bullets another 400 fps faster is using them totally outside of their design parameters, so you're really on your own. If you do want fast soft points, then use GS Customs, Barnes, or CEB, etc.
BTW, the best all around powder for these big low expansion ratio cases is quite possibly H335, with Federal 215 magnum primers, of course. It's very predictable from a pressure standpoint and, in general, behaves nicely. I'm sure that you can get a little more velocity from one of the new super powders, but I think that falls into the "why bother" category. Shooting the 570 grain bullet at 2500 fps means you really have to watch where you put your feet when you squeeze the trigger. If you're the least bit off balance, you'll certainly know it.
