ORIGINAL: RobertSubnet
With shots that crappy (sorry), I would be looking beyond the black powder.
When I am using a scoped gun and my groups aren't even consistent, I start suspecting the scope rings. Are they properly tightened? Did you use loctite on the screws? Were you able to bore sight the scope?
I am not familiar with BP inlines, but part of your problem could be similarto a problem I had with a Ruger 17HMR-the receiver was way out of alignment. I should have figured that out when I couldn't bore sight the scope. It took a trip to Ruger repair to get it fixed (which they only got partially right)
Best of luck.
Your right on on the alignment, It was off, I had a gunsmith install off set/adjustable rings on it. the only thing I had to do was after getting my scope back from being checked by Leuopold, was I ended up haveing to shim it under one end, I ran out of adjustment to get it on the paper. As for the screws, they are tight, everything on the mounts and all have all been double checked, like I said, with those "poor" shots, and don't be sorry, I agree, I'm seriously thinking of giving it up.