Here's a substandard 1 3/8" group with my Whelen using a Hornady 180 gr single shot pistol bullet.
The Lichner barrel is .625" at the muzzle, which is only .133" wall thickness. Normal groups are 1" or less at 100 yards and covering a 3 shot group with a nickel used to be common, when I was much younger.
It took three fouling shots to bring the group in and I believe the "flyer" in the group is where it still wasn't settled down (I've slept since then <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />).