Uh, no? That's a disadvantage. Numbers wise, the Coast Guard and National Guard could probably take on most European countries alone. The Marines are big enough to fight a war on their own.
And don't forget that when you finally reach US soil, you'll have American aircraft carriers and nuclear subs ready to surround you.
Those firearms are not an advantage. The Afghanis had/have AKs, PSLs/SVDs, some Stingers, RPKs, a few HK G3s, Enfields and Mosin Nagants and they were able to kick Russia's bum. Then the Taliban were able to fight the US military for over a decade, not allowing the US to retain control of 100% of the country.
You will be like Russia in Afghanistan. Like the US in Vietnam. But this time the underdog has both low-tech and high-tech weaponry.