PercyShelley
Member
- Joined
- Feb 15, 2007
- Messages
- 1,075
But even that is downright prosaic compared to the late WWII plans for a 15mm roller-retarded-blowback aircraft gun (I'm unsure if any were ever made), or for that matter the Becker/Oerlikon family of autocannons, which included the 20mm type 99 and 30mm mk 108. Becker/Oerlikon are often referred to as advanced primer ignition. However, if you do the math, you quickly come to the conclusion that advanced primer ignition can only effect a 50% reduction in bolt mass, and that in practice this figure is usually much lower than the ideal.
The handy US Army small arms design guide, helpfully hosted at Forgotten Weapons states that the correction factor for bolt mass on open-bolt fixed firing pin SMGs is .75, indicating that at least in small arms, API is about half as effective as the mechanical ideal.
Last edited: