I think you’re being overly simplistic - sure, ideas and debates have a place in politics. And “political power flows out of the barrel of a gun” doesn’t mean “Whoever has the most guns wins” (though this is the case most of the time) - but it does mean that a group with no guns has no power.
Like the other commenter said, the quote is partially metaphorical - it just means that force is the basis of political power. The people willing and able to apply the most force will almost always win in the end.
Think about in America. If, tomorrow, 75% of Americans were in favor of abolishing the police, would it happen? Maybe, but probably not - because the people with political power, the people with guns and the will to use them (cops, troops, fascists, small business tyrants) support the police.
History is shaped by material conditions; ideas play a part in this, but material interest is the primary driving force.