This is a custom replacement shell I made for buzzbee blasters, it has a 17/32 brass (like 12.6mm) fit at the base of the barrel and tapers to become a 1/2 petg fit (12.9mm) for optimal air use.

Added some new versions for the Mustang 6, and for blasters that aren't mag fed. the mustang 6 shells have a few mm shaved off the outside to help with proper loading and ejection, same with the looser outer shell files. I haven't tested them much but any of the longer shells may work in other blasters, allowing them to 2 half darts per shell or have improved performance.

the new "improved" file is a longer shell with a 13mm barrel and a 12.8mm stub at the base for optimal fps. I'm getting elite ranges with my over/under doubleshot and about 20ft more with my mustang 6

Consider donating me a few bucks if you like what I've made!