Ok guys i made a tnt cannon i know lots of users make them i did not copy anyone when making this i worked this out on my own it may or may not be like the others made who knows lol but anyway its all auto load and can fire upto 55 blocks away well the damage can go over 60 blocks away but anyway have fun with this one thing to note dont push the fire button more than once before it fires that can cause it to back up and expload its inside workings  witch im going to solve by putting a timer in there that only lets you fire once then your need to let the timer reset the fire button.