This is what I have, for elk and moose out to 150 yards,and possible bear encounter. .458, tsx 300 gr @2270 fps, tsx 350gr @2115, or 400 barnes sp original @1900 fps. all are equally accurate.would one be better than the other? Or would it matter at this distance?

My choice between those three would be the first, the 300 TSX at 2270. Those bullets need velocity to open up, and even the 300 gr will penetrate like crazy.

What caliber rifle is this. I see .458 but is that a 45/70, 458WM, 458Lott, etc.? I'm shooting the 300 TSX in my Ruger #1 45/70 at 2501fps. Just wondering why you have it down at 2270? Possibly shooting a lever gun or trap door?

rifle is a bolt action .450 marlin I had made. I had hoped for ruger #1 performance, but that hasn't been the case. It is more accurate than my #1 45-70 was, just not the velocity.

I have a Browning BLR in the same caliber, 20" barrel, and am getting higher velocities, but you may not need them. There is the Barnes 300 gr TTSX bullet that may be better all the way around. The tip enhances ballistic coefficient thus increasing down range velocity and energy without having to increase powder charge. My son used this bullet last year for an elk hunt with great sucess. I think it would also do for moose.