" Nobody makes a flat based 174 grain spitzer"
OT yes they do the Bullet Factory here (Over eastern states) makes 174Gn HPFB at .312" see pic the BF is on the left with the 174gn SMK on the Rt sorry for the above shot was from my I-Phone but the meplats on all the Bullet Factory are as uniform like you did them yourself and they are allot cheaper than the SMK.

I was one of the first to buy the BF projies ended up buying 800 of them.
As a side note I lucked onto 580 Highland 174Gn 303 projectiles a while ago these are not made anymore and were really accurate out of all my shooters I think I have about 900 of them now for a rainy day.
I am a horder I brought up on the SMK's when they were allot cheaper think I still have about 1,300 of them.