1. Stop production
2. Weigh remaining projectiles and determine if they are all of same weight or if there are other issues.
3. Odds are i'd pull each loaded round already and verify. You aren't that far into it, and let's be realistic here - a couple of extra hours of pulling, weighing, verifying and re-seating is well worth keeping your eyes or fingers the way they are now.
4. Contact the manufacturer and let them know of the issue. Give them whatever information they need (usually lot number on the box, caliber, etc.). I'd tell them you want replacement boxes for all you have that were bought at the same time and see what they say. 99.9999999% of the time the manufacturer will take this very seriously and work with you to A) make you happy and B) figure out what happened on their end as far as QC goes.
To answer your other question, yes, if you have the wrong powder charge with the wrong projectile weight, you could have a very, very, very bad day when the trigger is pulled.