If that is what he meant he did not make that clear, for me at least. He should have inserted "each" between "are" and "the".

I really don't think that is what he meant, Flintfan. Look at the first sentence in the second paragraph, where he mentions "overall length" of a shot shell not conforming to "the muzzleloading axiom in overall length". Sounds like he is talking about the length of the entire load to me.

SRH

May God bless America and those who defend her.