Inspired by Bolt's incredible FAR, I've decided to develop my own tactical nerf assault rifle. I call it the NP6.
1. Front Sight
2. Rear Sight
3. Picatinny Rail
4. Pump/Ejector Arm
6. Plunger Assembly Outer
7. Plunger Assembly Inner
8. Power Spring
9. Trigger Mechanism
10. Cocking Indicator
11. Pump Locking Mechanism
14. Magazine Release
15. Ammunition Level Indicator
18. Threaded Muzzle Head
19. Targeting Laser
20. Laser Thumb Switch
Above was my first attempt at visualizing the rifle. For the most part, the guns mechanisms are not to scale and difficult to decsern, but it served my purpose. I refined the drawing to this:
The NP6 (Nerf Pump 6) is a magazine-fed, spring-powered, slide-action tactical nerf assault rifle. According to my latest drawing, which is much closer to scale than the first, the weapon measures 32 inches from crown to butt. It is similar in principle to BoltSniper's hugely impressive FAR, but different in a couple of key ways.
Primarily, it's a slide action. That means that instead of working a bolt attached to the ejector port, the user charges the weapon by working a slide or pump. As the slide is pulled back, the spent casing is expelled and the weapon is charged. Returning the slide to it's foreward position closes the ejector port and advances another round into the chamber.
User pulls slide (light green) all the way back. Inner plunger unit (dark green) locks into place. User inserts magazine (blue). User advances slide and outer plunger (light green, connected). The leading, narrow end of the inner plunger advances the first round into chamber. Slide locking mechanism (dark green triangle) locks slide in forward position (locking mechanism is powered by a torsion spring, not shown, but represented by an arrow). User pulls trigger. Inner plunger is released and comes forward, driving the dart out of it's casing and through the barrel. As the inner plunger comes forward, it disengages the slide locking mechanism, allowing the user to cock the weapon again. User pulls the slide back. Slide arm opens the spring loaded ejector port while the extractor arm pushes the spent casing back and out of the chamber. Process begins again at beginning, minus the insertion of the magazine.
Over at NHQ, BoltSniper asked a couple of good question:
Your design looks very good. I don't see anything that will not work in your latest rendition. Not too sure how the ejection is going to work. Are you going to have a rim on the casings? Or am I right to assume the shell is going to be pushed out by the little tang on the slide rather than pulled by an extractor?
Also, why is the chamber so deep? Air seal? Cycle timing?
One comment about your plunger. I like the idea of sheathing the plunger to bring the catch point forward. Very clever. But I will warn you that plunger mass is your enemy. The lighter your plunger the better performance you will get from a given spring. A lighter plunger can accelerate faster and will produce a higher pressure behind the dart.
You're correct that the spent casing will be pushed out by the little tang-like thing (which I've been calling an "extraction finger" in my head) on the slide arm, but it's not quite as simple as it looks. The finger is hinged, and held straight by a torsion spring. It also has a rubber pad on the tip (the extraction finger tip, if you will). As the slide arm moves back, the top half of the finger is pushed inward by a wedge-shaped guide protruding from the left half of the inside of the gun. As the tip reaches the spent casing, it achieves maximum bendage and pushes the casing out.
To facilitate this, there will be a lateral groove cut in the left side of the chamber which will allow the finger to make contact with the casing.
The chamber is as deep as it is for two reasons. First, as you said, for cycle timing. The other reason has to do with this rather unorthodox extraction system I've come up with.
Most of the right half of the chamber is actually attached to the ejection port, and retracts as the port opens. This will allow the finger to push spent casings out, and still guide new rounds into the chamber when the slide comes back forward.
I've also taken a note from Mikhail Kalashnikov. If the gun is going to jam, it's gunna happen in the ejection port. By allowing the parts a little extra room to move and breathe, I hope to make the weapon a bit more resistant to malfunctions.
I'll take your suggestion about the plunger weight to heart. It hadn't occurred to me, but makes perfect sense.
I still have some developmental work to do on the gun. I'm in the process of rendering a couple of the mechanisms in more detail, and will post these as progress warrants.
Anyway, thanks for your time. Please feel free to ask any questions you might have or make any comments. I've already been given a lot of good ideas by community members, and I appreciate it greatly. By drawing on the collective knowledge of the community, I'm able to refine and perfect my design in ways that I otherwise could not. Thanks again.