Several years ago,I purchased a used 16" 45 caliber Gonic barrel. I hunted Connecticut with it( I had a stock on it so it was a very short carbine)
I really didn't like the barrel due to the fact it had a muzzle brake on it which made loading a real hand wrenching experience. It did shoot well, but cleaning the brake was a pain.
I haven't heard much about the Gonic line. He used to have a website but I see that isn't up anymore.
I did see some 50 calibers at a gun show and they were impressive.