Ti Rant 45 on .40 AR Pistol

I just put together a .40 cal AR pistol using a Q Circle10 barrell and bolt. I want to put a Ti Rant 45 on it but for some reason they threaded the barrell 5/8 X 24 and AAC does not make a piston for that thread. My options are 9/16 X 24, 9/16 X 28 and my preference .578 X28. I have been looking for .40/.45 adapters but so far no luck. Any ideas?

Ti Rant 45 on .40 AR Pistol