Rough trigger mechanism design

     I am considering using a trigger mechanism similar to the one in this picture. It will consist of a rotating trigger (the blue piece) and a spring-loaded falling sear (the grey piece).

     The sear will have two springs applying a downward force on the it. When the trigger is at rest, the strength of the trigger spring will keep the sear in place. As the bolt moves the plunger back, the plunger will push the sear down until a notch in the back of the plunger (the orange part) moves over the sear and the trigger spring pushes the sear up into the notch. As the trigger is pulled, the sear springs will push the sear downward and ultimately out of the notch, releasing tension from the plunger spring. My main concern with this system is that it will likely be sensitive to spring tensions and a delicate balance will likely be necessary. If anyone has an idea of how the spring strengths should relate to each-other mathematically, please leave a comment detailing such.

Designing the Lower Assembly

     I had some struggles deciding how to make a trigger system that would fit a 1.25" PVC pipe because the only designs that came to mind that would work with my plunger system were of the type found on the Nerf CS blasters, which were big and oddly-shaped. When I got home and took a look at an old airsoft M4 I had (which happened to have a transparent shell), I realized it had roughly the same plunger system that I have in mind for my blaster.

     This is the receiver from the airsoft gun in question. The trigger is both simple and effective, if a little rough. One problem with the trigger piece is that it was made for a gun that had a trigger in the middle of the receiver, whereas I would like a trigger at the back of the receiver for my design. Ultimately I can imagine this to be a simple fix.

     In other news, I have downloaded a program called Autodesk and have begun to make a digital mockup of my blaster design. You can expect me to publish images of the model in the future.

Rough Action Design

After looking up mod kits on eBay and simultaneously watching GMod videos on YouTube, I have thought up a design for the action and have drafted a rough MS Paint mockup of it.

It uses a direct plunger which is hollow and open  on the back end to fit the mainspring in. The bolt is held in place by two tabs on the side and will have a charging handle directly attached to it.  I know there is no barrel or tigger assembly yet. This is just the action.

Entering Homemades Head-First

     I am planning a homemade rifle that in hindsight seems quite ambitious for someone who isn't even good at modding. I've done some research recently which, in addition to my standing knowledge of construction and engineering, has given me a rough idea of how to go about building my rifle. Chances are this is going to take several months and I will not be working alone, mainly due to college struggles. Then again who does anything completely by themselves these days?

     I am primarily shaping my rifle concept on the basis of the Gustloff Volkssturmgewehr, with design influences from the Sten Mk. III and the L2A3 Sterling. For the action, I'm stuck deciding between a conventional plunger action and a more elaborate pistol-type action. It will be fed from a detachable box magazine, just like the three weapons I'm drawing from. Construction will be mostly plastics, but I'm considering using an aluminum or brass barrel, and there's a small chance it will have wooden furniture. More details in due time.