You'll find a cheap digital scale invaluable w/ xbows. Google mfgr of your bow and find listed min weight arrows.

Imho, 110 gr brass insert and 150 gr Boltcutter passes the point of no benefit in FOC. My 20" Gt's, Blazers, brass insert, and 100 gr points come in at about 18% FOC, about 400 gr. I shoot a recurve, that weight is below min for some compound xbows.