It’s simple. All they have to do is get 67 Senators and 291 Representatives vote to overturn the 2nd amendment. Next it needs to be accepted by the legislatures and governors of 38 of the States(there are 27 states controlled by Republican legislatures and 29 Republican Governors). Then they get to come and get the guns. Simple
Hmmm...... 50 states minus 27 w/Republican legislatures = 23
50 states minus 29 w/Republican governors = 21
IMO, that’s beaucoup Republican controlled states to provide the 15 or 17 additional states for a three fourths ratification of a Constitutional amendment, the sole purpose of which in this case would be to overturn an existing Amendment that is one of the Bill of Rights.
It’s been done only once, when the 21st Amendment repealed the 18th (Prohibition), which had been ratified only twelve years earlier. A move in Congress to repeal the 2nd Amendment will trigger insurrection, and they know it.