Variations of less than 30-50fps should be tolerated given the kind of equipment available at any gun store, and level of technical competency of the average reloader. I've seen loads vary by as much as 100fps (not mine), but those loads were done by people doing mix-and-match on components and didn't do a good job with their powders and seating. I don't use their ammo.
Since you're asking about brass, cases from different manufacturers loaded identically can have different results on POI and velocity. While the external dimensions may be the same, internally they can have different volumes, and thus different pressure levels.
The guy who taught me how to reload said that the key to good loads is consistency, and that means finding the right components and measurements and staying with that magic formula.