Nice ! I made a similar breech block riser for my 2260 to run a shroud. I will post pics. I sent Firewalker a DAR stack earlier this year... I wonder if that is the same or if he swapped stocks and sent you another. I never thought to try the 2260 tube in it. Looks good !
Wow! What a true Frankengun! That's more parts from more different brands of air guns than I think I've ever seen merged together to creat one really nice looking air gun! Very well done!