Another thing you could maybe try would be the TC Shockwaves...

[Linked Image]

They make a .50 cal combo that shoots a 200gr. 40 cal projectile. TC says they'll work down to 1000 fps. Might be easier to get a XTP at working velocities but just another option.

My dad shoots these at 2200 fps. They are accurate out of his gun and penetrate well.