I completely know what you mean when you say it had 00 buckshot accuracy. When I first bought the rifle for a hunting trip, I picked up some of their E-Tip loaded ammo. It was a little pricey, but you know what they say "You get what you pay for".
I expected it to be great ammo. It did there 3.5" to 4" groups. So I put the last 5 rounds away. Some time later, I pulled it out and measured it. The Ogive was jammed 0.060 into the lands. That explains it. I hope this next go around is a little more rewarding.
Does anyone have any suggestions with some of the other lead-free options.