Finally patterned the gun today- did the 16yd method described earlier. Just mounted and shot as if shooting at a bird. Did the same thing at 20 yds and 30yds. Gun seems to pattern fine now- maybe a 60/40 split high-low and centered. Both barrels are shooting to the same POI. So not sure what the problem was- I only shot it a few times the first time before I saw it was loose, but next I need to get out and shoot some clays with it.