Once again, this is not based on experience with the 500, but rather a little with .44 Mag and a lot with .45 Colt, but you said that all the information you found was relevant to revolvers but not your handi-rifle. Due to the velocities you are talking about, I believe that the revolver information is EXACTLY what you can expect out of your rifle also since you are talking about the same bullet moving at the same velocity, and the only difference being the launch platform. Assuming I am thinking correctly, and based on experience with .44 and .45, I would personally stay away from spitzer type bullets as you mentioned, which tend to zip the target animal with less effect than the same weight or even a slightly lighter flat nosed bullet would. With your stated 150yd range limitation, I really dont think the flat nose will have any detrimental effect on accuracy or trajectory, but will give you a huge advantage as to terminal effect on target. I am not trying to sell you on the LEE mould, but unless things are very different in your area, I would think that buying the mould and casting your own, especially since you said you used to cast years ago, would be easier and cheaper than having to buy bullets all the time. So I would say forget buying bullets, and buy a flat-nosed (wide meplat) type mould of your chosen weight, brand, etc, and go that route. And even if the .50 BMG mould you found is what you choose, there are many different size sizing dies available, so you can always size it down a bit if it casts a little too big for your needs. Happy hunting, and let us decide what you end up doing and how it works? I love my .44s and especially my .45s, but the 500 just seems like a bigger and for this application a better hammer, so I'm sure you will be happy with it.