Remington Gun Club Hulls ball fits perfectly in the hull. Nice thick plastic case, one piece construction. I am using this case to test out fist, seems like the best cheap hull.

Fired 28.5g of IMR 4756 with a Win AA White and Remington power piston stolen out of factory loads. 1050 fps Had cut the pedals down to cup the ball but found the base of the shot cup caved in and supported the ball on it's own. 25 yards ma bey 6" group with a Mossberg pump smooth bore bead sight.

Fired 31g of IMR 4756 with used Remington Power pistons 1170 FPS 6" group at 25 yards. Shot this load through a frozen 5" poplar tree and stuck into another one 2" deep. Ball looks unfired no deformation. (air cooled WW but the air was -10*c) also pulled a ball out of a frozen dirt bank, little to no penetration ball looked unfired so I shot it again!