I love tube guns, hugh fun factor.
Well I decided to design for my CAD class project and portfolio material a 9mm machine pistol. My instructor agreed to my doing this but I have to flip it to a semi auto only design. It's originally designed as a square tube reciever w/ a piece of high pressure hydraulic tubing for the barrel. I'm gonna flip it to a tube reciever, semi auto, closed bolt, floating firing pin, AR style ejector pin, and either design my own disconnector in conjunction with the supplied trigger group design or use a AR style trigger group, and a AK style guide rod w/ spring. And of course a rifled barrel. I have to make it pretty for him. So I'm thinking ventalated barrel shroud, custom pistol grip of some kind, and G3 style sights. And he wants me to show the various springs compressing and de-compressing in Inventor. All drawings will be in both AutoCAD '09 and Inventor '09. So wish me luck.
ok now my ignorance is gonna show. please expound on the feed lip issue as I do not know what your refering to. I took the idea for the ejector from the AR bolt as the original design did not have one.
First off I would like to just say thanks for taking the time to explain this to me. I do greatly appreciate it. This why I posted it here becuase I knew if there was any mistakes or booboo's someone would point them out quickly. I 'm really pretty good on most of these things concerning the laws however that particular item is new to me. Now to try this again as my post was denied /deleted becuase it seems Gunco forgot I was logged in.
Ok one more time. So if by making a custom/one off closed bolt semi auto pistol w/ a floating firing pin I have to grind flat the bottom of the bolt where the feed lip is so this will somehow prevent the floating firing pin from somehow jamming in the fwd position and thus allowing the gun to go full auto? All becuase I chose to design/build a tube gun? All I can say is wow............. Sorry for my sarcasm, I'm just amazed is all.
So would this also apply to a square tube reciever as this was the original design of the weapon. If not I'll go back to the original design and go from there. And again thanks for taking the time to explain this to me.
And also the reason this matters is I did promise my instructor to make sure as best I could that the design would be in compliance with applicable state and federal laws. So this why I keep asking questions.
No one has ever accused the atf of being fair or consistant.
On a full auto open bolt gun, the firing pin is sticking out of the breechface. This is how they work, as the round is chambered the cartridge bottoms out in the chamber and the bolt continues forward, slamming the pin into the primer and firing it. The breechface of the bolt has to be recessed for this to work, otherwise the cartridge would slide up under the extended firing pin and jam against it instead of riding in front of it. By removing the bottom part of the bolt and making the breechface essentially flat where the cartridge is fed from the mag you prevent the possibility of someone jamming the pin forward and letting it go full auto as the cartridge will slide up under the pin and jam against it. The M11 nine series of semi autos, for example, still has this fully recessed breechface on their bolts even though they are semi auto. If the firing pin were to get jammed in the forward position you would have a runaway full auto as there is no way to stop the bolt cycling other than a jam or running out of ammo. A safety issue as well as a legal one.