First of all, I am sure you have heard of a caliber that has killed a LOT of elk and buffalo in its time: The 45-70. Those numbers mean that it was 45 caliber and used 70 grains of blackpowder. Thats right, only 70 grains! When you are flinging big hunks of lead, you don't really have to used magnum charges to get great penetration and terminal performance. Here is a good reference to read:
http://www.loadammo.com/Topics/July02.htm Talks about how big slow bullets have great knockdown power. My load: 80 grains of 777 is the same as 92 grains of blackpowder since 777 is aprox 15% stronger than BP.
As far as using 150 grains of powder for a 500 grain bullet? There are people who do it, but I won't be one of them. The recoil on that would certainly be big. If you plug my load into the Taylor index, you will see that it has plenty of "knock down" for elk. Why would I want to put up with more recoil when I have a very accurate load and I don't flinch from recoil?
Also, for some reason, in my experience, bigger bullets fly better at lower powder charges. This is probably not true in all guns, but it certainly is in mine.
Also, as you increase the lead weight, you also increase the pressure you build up in that barrel, so you have to be sure that you have a barrel that can withstand the pressure. All barrels are not created equal.
Most people who use magnum charges with big conicals do so for a couple of reasons. I think the main reason is they want to flatten the trajectory out to shoot at 200 + yards. And most just seem to "like speed". In my case, I only hunt in Colorado with open sights, and am content to set a max range of 100 yards. There is no need for magnum charges in my case for me.
Many bullets, powerbelts for example, seem to perform better at lower speeds and break up when you start pushing the limits. In their case, you actually seem to get better penetration at lower charges because the bullet holds together better.
JMHO
txhunter58
venor, ergo sum (I hunt, therefore I am)