The US is a representative, constitutional democracy and a federalist republic. What does government oppression (aka tyranny) look like in such a government?
Amending the Second Amendment would take overwhelming public support
Amending the Constitution is intentionally difficult, requiring 2/3rds of the House and Senate to pass an amendment and ¾ of the states to ratify it. Amending the Second Amendment would require an overwhelming supermajority of Americans and a tectonic shift in public opinion about guns.