I wasn't shooting bowling pins, but have loaded cast bullets up to 158 grains in 9mm. So long ago, can't remember powder, velocity, results etc. But have you tried the factory 147 Speer Lawman flat point, or factory IMI 158 grain? I've not tried the IMI 158, but IIRC the 147 Lawman averaged 1100 fps or so in my 16" carbine. These might give you a baseline to shoot for in future reloads, if either is more effective at knocking down bowling pins than your current load.

FWIW, I think those guys shooting the heavier and larger diameter bullets are always going to have the advantage at knocking down bowling pins and steel.......

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