If you know your BC and a true velocity, StrelokPro, AB Mobile, or Hornady 4DoF will have you within two clicks at 700 yards. 18.5moa is pretty close to making sense for that load.
Running it through Hornady 4DoF and StrelokPro, I get 18moa at 1000ft DA (not actual elevation, DA) out of both calculators, so 18.5 would have to be very low elevation, as in negative 1500ft density altitude. I’ve shot in negative DA’s, but never -1500ft. But like I mentioned, these proven calculators will have you within 2 clicks, half MOA, so a discrepancy between yours and mine of 5” at 700 isn’t so surprising (or maybe you really are shooting -1500ft DA?).