There is no specific federal "magic number" of firearms a person can buy Oliver. The flagging and reporting requirements are based on the number and type of firearms sold by an FFL within a specific timeframe. The ATF automatically flags certain multiple firearm purchases by requiring licensed dealers to report sales of two or more handguns or specific semi-automatic rifles within five business days to the same unlicensed buyer. These reports, submitted via Form 3310.4 for handguns and Form 3310.12 for certain rifles in specific states, help the ATF identify potential firearms trafficking and illegal gun movements. Multiple sales are considered strong indicators of trafficking and are associated with increased likelihood of firearms used in crimes and recovered from crime scenes.
Check out the following link:
atf.gov/firearms/reporting-multiple-firearms-sales-or-other-dispositions
As long as you're NOT doing anything illegal you should be good 👍🏻