That does seem weird, but that is also what eagle 6 says http://eagle6.co.uk/shop/catalog/product/view/id/959/s/tokyo-marui-scar-l-h-original-inner-brass-barrel-300mm-for-scar-next-generation-recoil-shock-series/
Hmm... they have the m4 ones down as 6.08 which makes more sense, I'd assume it was a mistake but its not like it could be 1 key slip or anything