A humane kill involves more then just the speed of a projectile. But how the projectile is made and how it reacts upon penetration.
I'm sure if the piece of piano wire in the example below hit a deer in the boiler room, the wire would have went clear through and the deer would have died as well. But would it have been as humane of death as say a bullet designed with adequate penetration as well as expansion for a quicker kill?
A piece of straw can penetrate all the way through a palm tree if propelled by hurricane-force winds.
Propelling a piece of straw at a palm tree at a distance of 50cm at 320mph (the world record for recorded wind speed at ground level), the straw only managed to penetrate the tree a quarter of an inch. Even firing at the tree while it was bent (to increase the size of the pores in the surface of the tree) at point blank range added no additional distance into the tree. A piece of reed was tested as the sturdiest organic object that might be mistaken for a piece of straw. At both ranges, the reed only managed to go about two inches into the tree. Additionally, Jamie tried a piece of piano wire, and at 50 cm, it flew not only through the tree but through a sheet of plywood on the wall behind it, partially embedding itself into the cement wall
My point is, there are better bullets designed other then the FMJ or SP that are going to be a better hunting round. Giving adequate performance of expansion as well as penetration. If not, then why would we compare hunting with the M1 to even the less powerful, but still adequate .357 that does offer a bullet designed to expand for a quicker kill.
I would no sooner hunt with a FMJ out of an M1 as I would hunt with a FMJ out of a 30-06. Same as I would not hunt deer with my bow using field points which will penetrate completely through a deer leaving a small hole versus using a broadhead which creates a much larger wound channel creating way more blood loss resulting in a quicker death.