Unfortunately the U.S. Constitution infers the ability of states to remove liberty, life, and property. Included in liberty are your "rights". This is from the fifth amendment:
nor shall be compelled in any
criminal case to be a witness against himself, nor be deprived of life,
liberty, or property, without due process of law; nor shall private property be
taken for public use, without just compensation.
Although this can't be done without a jury, and sentencing. It seems legal to bind with certain crimes, the mandatory loss of the RKBA.
What can't be done, is just take away everyone's right with a new law, and no jury. The problem is, it seems they could bind the loss of the right to gun ownership to moving violations, if they just made them jury trials.
That being said... Laws can't be retroactive. So in theory, since the previous juries did not know they were sentencing the penalty of losing their RKBA at the time of trial, any felony conviction from before the first GCA, can't be legally kept from purchasing firearms.
Now in RL, they will take our rights away. I'm just stating we don't have much of a guns for felons argument. The constitution does support loss of rights after a jury trial. Not to mention, you won't get many people to join your "GUNS FOR FELONS" initiative, except felons, who can't even vote in most states.