Whats the barrel diameter at the muzzle???
It can't be larger then .950" which includes the muzzle brake
if it has one on. (16 1/2Lb class)
How wide is the stock at the forend? Can't be wider then 3" for the 16 1/2" class.
What twist is it?
If it's not an 8 twist it won't stabilize the 107 gr bullets which is popular in the 6mm diameters. The smaller bullets don't seem to shoot well at that range.
Just want to make sure you are legal. If not, it will have to go into the Heavy gun class.