Those arent 19 inch guns, and i could of told you that without a measuring tape. But Bigmc provided the tape and all it did was prove what my initial analysis was....
From the 19 inch mark to the very bottom of the visible part of the arm, you can see that there is 5 inches.
From the 19 mark and above , which is basically the peak of this bicep, there is only 2 inches.
Now take that and multiply it by two (to represent the rear of the arm, and you only get 14)
So your saying that your arm's bottom is nearly the same as the total front measure ? ie extra 5 inches? judging by your forearms, i doubt were looking at a freak of nature.
Bigmc's Arms 16.5 tops...
Thats me giving him a half inch on top and 2 inches for the under part of his arm.