Well I'll find out tomorrow,I am pressing out the barrel and machining a .20 caliber barrel for it.
Just have to try a .20 caliber shadow, I have a couple of Walther blank barrels to play with.
According to Dr. Beeman this "IS" the caliber for an air rifle.
Talked to JH and he told me the choke on these barrels need an adjusment for maxium performance, he also said he has a couple of hundred of these barrels. Will let ya know when it's finished and how it preforms.
Then I will have shadows in .177, .20, .22 lot's to play with.