Exactly correct. It is a non-argument. The left loves to make up slogans which sound as if they mean something, but are mere emotional pleas.
"Military grade" simply means ammunition suitable for military use.
The emotional plea comes from the slogan "Weapons of war don't belong on American streets!". It is merely a slogan which is silly, without merit.
Pistols are weapons of war. By the slogan, all police officers should be disarmed.
The slogan is an extension of the emotional plea: Guns are bad. It is a statement: I don't like some people to have guns. Therefore, use the power of the government to prevent people from having guns.
“Weapons of war don’t belong on American streets!”.
That claim was used in the 1960s to get the import of 5 shot bolt action army surplus rifles banned in the US in 1968.