WHAT DOES 18.5″ BARREL MEAN?

So following a couple months of owning this firearm, I've 1 big problem to reply. Can it be pretty much as good as being the SP5K and which one would I choose? In the past, I’ve shot equally a good bit and don’t get me Completely wrong, I absolutely like my SP5K, although the much lessen price of the AP5-P combined with the general Create high