They look pretty well made. A little more emphasis on expansion than on aerodynamics.
The design makes me wonder if anyone has done a comparison in the performance of firing a slug vs. a pure circular cylinder. Not sure what that would be called. A "slug blank" perhaps?
He shows some expansion on gel & it looks pretty good. One of the videos he explains why he went to pure lead for expansion. I may have to get some to try out. He gets some pretty good accuracy from his rifles, but I haven’t seen any of his rifles that has a CZ barrel like my Caiman X.
Lead cylinders are often referred to a trashcan round, or wad cutters. And I know some people have tried them, but I've normally seen them with grooves to reduce the barrel contact.
They work in firearms reasonably well, so should probably work OK in airguns if you can get past the choked barrels.
I really would like to see some expansion testing on pigeons to see if the sticker price is worth the extra money....
I imagine something like this (and I have started a similar test series with.22cal hollow point pellets):
• At least three test shots into dead pigeons (side), to provide a reliable test.
• At reasonable impact velocities: 700fps, 750fps, and 800fps (either dial the velocity down, or increase range to cadaver).
• Catch the projectiles with a 6" pipe or deep box filled with material to slow down the projectile without deforming it: I use plastic bags and loosely bunched clothing.
• Measure the expansion of the projectiles.
Whenever I can get my car running again I'll head out to the big permissions to continue testing!