PullPup V.1




Introduction: PullPup V.1

About: meh... is this textfield necessary?

sorry, sorry, yes I know it's yet another gun made just to show off a mech... don't worry, I promise to try and make a performance rifle after finishing this one, just please do read this one as well since this has a ton of really cool mechs within (also I have a request but I'll do that at the end)

So I noticed that, aside from the BAR and a couple derivatives, knex Bullpup either have a really short pin and crappy range with a big stock behind the mag, or they have a pin that sticks out the back. I figured, why not put that pin in front of the round? why not pull it out instead of pushing it out? I set out to do so... and this monstrosity is the result. The thing basically throws cosmetic design out the window, and yet still has problems... no, this is not likely to be a war weapon any time soon, maybe never will be. But... this is just a concept ible so stay with me as I try to explain the mech in a fairly simple manner.

1. The pin (two black rods with orange connectors at one end with a cut white between them) is pulled back, and slides over the chamber holder so that the white piece is at the very back of the gun.

2. The raising mech is lowered down to the level of the magazine

3. The round injection rod is pulled back, pushing the round out of the magazine and onto the raising mech tray

4. The tray is pushed up, pushing the round into the chamber and holding it there between the black rods in the pin, the top of the chamber, and the tray, with the white rod in the pin right behind it

5. The imaginary trigger is pulled, letting the pin fly forward and push the round out of the barrel towards a target

this is where the request comes in... I need someone good with triggers to help, I've figured out a catch for the pin, but a working transfer system for a trigger that isn't a huge box on the outside eludes me

also, I want to figure out how to make the chambering mechanism easier to operate, even operated by a motor if possible. anyone who gives me a good idea automatically gets a follow from me I'm so stumped with this problem, with both actually.

Without further ado, the pictures.

Step 1: Photos

if you want more pictures then comment with what you want, I'm kind of hoping to get it working well instead of basically just ejecting the rounds out of the front. thanks in advance for any help!



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    20 Discussions

    Working on version two with fewer moving parts but same basic concept. Stay tuned, I'm pretty confident I'll be able to get a gun with 40ft of range from it

    pretty much

    I was hoping to have more time so I could get a better gun up and a good instructable but alas...4 school projects to "make use of the long weekend" :/

    So a hammer hits the pin forwards like bands push a pin forwards in a traditional pin gun?

    1 reply

    there is no hammer, the pin simply is shaped like a U and the bulled goes between the two sides of the pin and is hit by the bottom as it moves forwards

    Very cool! I had an idea for something sort of like this but it used a rail car to pick up the ammo out of the stock and shoot it out of the rail car when it hit the front of the gun. Here is an idea you could try a pump action rail action.

    I'm thinking maybe making a repeating rail based sniper... thoughts?

    yes I know it looks worse than a lot of unmentionables, but... the reason for it is to be able to fire from a mag at the very back of the gun. the chamber on this one is less than 3 inches from the buttplate, so the proportions could theoretically be more realistic. I guess I really do, at least right now, have a very unique style... :p

    update 1: I managed to reduce friction somewhat by shimming the barrel to be one blue washer wider, still trying to figure out a good trigger

    any ideas for the trigger transfer mech? here are some pics of the internals in that area


    Thank god, someone is finally trying to figure out how to make bullpups efficient, as well as being back some innovation to instructables. Good luck with getting it working well.

    2 replies

    when it comes to bullpups IDK why I just like the idea and the look of them. in knex probably the main reason to build them is that you get to show off your bad***ery when showing everyone that yes, the 8 bazillion part mech does indeed work... and most shots too :p

    lol thanks, if I get a working trigger I might be able to work some of the friction out of it. as is, the barrel guide inside of it comes to a new joint after about 7 inches, after which point the round is no longer propelled by the pin. I think if I resolved all that extra friction I could get 35ft ranges out of it, but I really need to get the trigger first at the moment.

    I don't know if you ever saw this, but this is Johnny Be Goods Competitor 5 and it did not work well when I built it but I think it has a ton of potential for bullpups IMO since it can be so compact, but I think you should try getting this to work in a bullpups since you seem to be the bullpups man right now.

    15, 3:51 PM.jpg15, 3:51 PM.jpg
    1 reply

    so it's a pin with a hammer on the back instead of a linear band pull? doesn't sound that hard, but without an impact based hammer doesn't sound like it will get great range either. maybe a catch so the hammer can swing forward and hit the pin, but pull it back a bit when re cocking to allow the next round up