Short plunger concept

Hey, just looking for a little feedback on something I'm working on. some time ago I mentioned I was planning to start designing a dart blaster from scratch. Well, I got halfway through a few designs and ran in to some obstacles to do with the internals taking up too much space lengthwise. However, I've figured out a way to still have a big plunger tube while having a short overall length. basically it's a variation on the Retaliator plunger setup, where the catch grove for the plunger is down near the plunger head. this moves the catch plate from the end of a big plunger rod to the back of the plunger tube. there is still a plunger rod on the retaliator's plunger, however. I believe this is prevent the plunger flipping over in the plunger tube, and also acts as a spring guide.

SO, with this idea, the plunger, catch edge, and spring guide are all contained within one small unit that features a simple design with no "sticky outy bits", which allows it to be moulded, printed, forged or machined on a lathe. it's simple design is theoretically strong, as there is little that could tear away or snap, and the lack of plunger rod also means a lighter weight, increasing plunger acceleration.

the twin o-rings allow for different resistance through use of thicker or thinner o-rings, and also stabilises the plunger. the depth of the spring guide can be machined to the compressed length of the spring used, and spacer washers could be used the put higher compression on springs with a shorter compressed length. the catch edge can be as wide as the inner diameter of the plunger tube and can be designed with different taper.

this is the start of the design rendered, feedback appreciated!

Very nice! My only thought would be to ensure an all-round uniform sear catch, to properly distribute the lateral stress you'd likely encounter with the plunger barring against the edge of the tube (if you were to use a single-point sear catch). Something akin to the Longshot sear catch, or a modular rainbow catch would be good.

I've had the plunger-rodless concept floating in my head for a while, it's definitely a space saver. Are you thinking of cocking it on the backstroke, from the front, like an LS bolt does?

Definitely going to use a catch similar to the longshot, with tightest tolerance possible without impeding on reliability, but i'll also probably add some rounded edges to avoid damage in the event that the plunger scrapes the tube, but hopefully the right o-ring placement will avoid that happening. It'll cock the same way as a longshot, with the back of the breech pushing it back. hopefully this will be small enough to make way for spring powered bullpup designs.

Combine this with a shorter dart and breech, and you've definitely got the makings of a bullpup blaster