There was this foreigner from the middle east shooting birds close to 200 yards with his who used to post but was bashed for unsafe backstop. I can verify that it's capable out to almost 200 yards with MOA base and Burris Signature posalign rings once you get the trajectory down packed.
I think his site was zapped during the great youtube purge. I have two D56s ( 177 & 25) and now two D54s (22cal). I will put the TO5 D54 up for sale sometime in the future.
I was looking into one also.
Did you tweak your Bullseye mount at all?
I've heard some say its got play in it?
The only thing I did to mine were to spray some WD-40 silicon on the rails. They are pretty sturdy and I've never had any issues with the three I have mounted on rifles. My gun like the H&N FTT pellets. I had a magic tin of Crossman ultra magnums that were the most accurate pellets I ever shot in a springer. I've yet to find another tin that shoot as well.