How are you deducing the nock left tendency at distance? I assume you're looking at impact angle in the target, not actually shooting through paper at 20+ yds. Impact angle can be misleading due to inconsistencies in the target medium. Shooting a bareshaft alongside a fletched shaft or a fixed blade broadhead alongside a field point at distance will tell the true story. If your arrows truly are flying nock left, the bareshaft will land to the right of the fletched shaft and the broadhead will land to the right of the field point.
Paper tuning is good for getting started but isn't a complete replacement for bareshaft or broadhead tuning. I always shoot through paper at two distances (6 and 20-ish ft) to confirm my tear before making any adjustments.
Conventional wisdom (nock left tear = arrow is too weak, nock right tear = arrow is too stiff for a right-handed shooter) would say your arrow might be weak (assuming you are indeed a righty and truly are getting nock left flight). But 250 spine would actually be on the stiff side (per spine charts) unless your arrows are 30+" long with really heavy inserts. I think the conventional spine vs. tear advice is a holdover from the days of traditional bows shot with fingers and isn't applicable to a compound bow shot with a mechanical release. I highly doubt that arrow spine is causing any problems for you.
