147 is more popular for competition use. The felt recoil is less. You don't have to push them as fast to make the power factor. I use a Dillion progressive press than can easily load 500 rounds an hour of handgun ammo.Curious, why 147gn in the 9mm?
A few years back talking to some of the engeeners at Sig they did a test with ammo and the rate of wear on the barrel. Two identical AR's and they fired brass and steel through them. Using steel the barrels wore out several thousand rounds sooner.
Not an issue if a few hundred rounds per year are shot. And that's probably the norm for most users. Same for frangible. That eats up barrels in the quantities shot by the senior instructors. With new facilities, they no longer have to use it as much.