The question has been raised about why shoot 175 gr charges with a .62 roundball. The Zephyrs are modeled after the African big game rifles of the nineteenth century. Their slow-twist Forsyth rifling is meant to achieve maximum muzzle velocity from a PRB, resulting in a flatter trajectory and higher downrange energy. The muzzles are ported to reduce recoil. They recommend a maximum ethical kill range of 125 yards. This is significantly longer than can be achieved with lower charges, and faster-twist rifling. It would also be more effective on larger game. For deer hunting, they recommend a load of 100-125 grains.
Their Alaskan (12-bore) and African (8-bore) models have maximum recommended loads of 250 and 300 grains respectively. These are intended for use on large and/or dangerous game.
While these large loads are not for everybdy, they DO have a purpose in certain situations. I was not recommending this load but posted the ballistics chart in answer to the original question of this thread.
Jimbo