A) Place slug loaded gun in forked stick, on gorund, up against tree, cushioned by many pillows. Run string from trigger to another tree about 50 feet to the rear. Using string, pull trigger. If the gun is okay after this test, then it is okay for you to shoot those slugs out of it when you have to.
Plan B) Cut open a slug and mike the slug and add the hull thickness times two and figure out if it comes out to much over .729 (the hull is a little compressible). Actually this is rather conservative, because even short forcing cones are more than 1/4" long.
C) Do nothing different than you have been; just figure if it doesn't work you would rather be killed by a gun explosion than a buffalo.
D) Buy a hell of a drilling.
E) Buy a PACK of wolfhounds and train them to point, or heel, or both.
It is not MY LIFE, but I would bet a little of my money it will work fine, because slugs are a little undersized and forcing cones do exist. They figure some folks have full chokes you know.
