No1-25 Cannon

This is a straight blow back cannon. I designed this inspired by the MK108 using the 25x120mm in this case (see what i did there? *case* hehe) which has the same base dimensions as the 13/15x120 and 20x120. This would only require a barrel change to chamber the other cartridges. Like the mk 108 the bolt carrier goes into the barrel to increase the time the case is supported. However this mainly works with straight walled cases, which my 25mm is. Furthermore, the other two are not, so they could expand and cause a failure to exract. To remedy this, the bolt carrier withdraws a little farther than it has to and the ejection port is very large. This is electrically fired with the electrodes being the recoil spring guide rods. It is also closed bolt so could be mounted in the cowling of an aircraft and fired though the propellers. The BF-109 mounted the MK108 in the propeller hub but that is not always practical. The name for the cannon is the MK1 but the 25 part is the caliber since it can change. This could also be the MK1-20 and MK1-15 (or 13 depending on whether i decide to call it by the caliber of bore size). The barrel has progressive polygonal rifling.