As I already mentioned, Remington make a 174 grain, flat base FMJ projectile in their line of Remington-UMC target ammo. I'd guess it's loaded to Mk.7z specification but most don't want to pay the price per box. Dealer cost on the ammo is $21 and change a box. It simply doesn't compete price wise with the PPU and S&B that's produced overseas to Mk.8z spec.. For many folks, reloading is the only option. Some may remember when I tried in 2012 to get the engineers at Sierra to think about producing a Mk.7 projectile or at least one with the same flat base performance and failed miserably. I supplied pulled nos projectiles and dimensional drawing etc but to no avail. Of course, if I had dropped thousands of dollars up front, they would have done a run but that ain't gonna happen. I think all of the big bullet manufacturers are missing the boat on this one.
Remington should market the 174 FB FMJ .311 projectiles in bulk like they do 7.62 and 5.56 but they don't do it. The problem would be solved.