Ar-15 Bullpup Lower Technical Thread

[Wantabe_ Warrior]

Hello CGN’ers, earlier I was thinking “Man, the Tavor seems to have WAY more crap on the frame than I needs. Unlike the AR-15.” a little while later I start wondering and thinking about if it is possible to make a bullpup AR-15. I then start thinking about “How?”. NEW LOWER! So new lower = new gun, If I’m thinking of a new gun, let’s try for an unrestricted rifle (Thinking of the ATR Safety Harbour Lower).

A) For this lower (idea) I was thinking:
1) Remove the pistol grip mount from the receiver, move the pistol grip onto a picatinny mount with a trigger
2) Change out the the trigger from the Fire Control Group so that it can be connected to the forward trigger. My thoughts were the trigger and FCG were connected via wire (like bicycle wire)
3) Remove the buffer tube.
4) It then dawned on me: “Where would the bolt go then?” So possibly limit travel, use a longer receiver to capture the bolt and spring, and/or use a shorted bolt/spring combo or a combination of these ideas. (Please remember: I have little understanding of what makes AR-15s work, as opposed to what makes it go ‘Bang’)
5) Move your sights/optics forward, throw a picatinny cheek pad onto your existing AR-15 upper, and mount your pistol grip/trigger to your lower picatinny rail.

B) To Do:
1) Figure out a system to be able to work the charging handle forward of the buttstock.
2) Figure out a system to move/use the safety in a more forward position.

My original thread for the idea: http://www.canadiangunnutz.com/forum/showthread.php?856157-AR-15-Bullpup-Lower

 

[TheWharGoul]

Other then using the AR-15 magazine and grips I don't see how you could use uppers or parts of. You'd need to create a completely new lower and upper. Could they borrow features? Sure they could, You could take features from a lot of different designs but it could never accept AR uppers if that's what you are after.

 

[Wantabe_ Warrior]

Other then using the AR-15 magazine and grips I don't see how you could use uppers or parts of. You'd need to create a completely new lower and upper. Could they borrow features? Sure they could, You could take features from a lot of different designs but it could never accept AR uppers if that's what you are after.

I'm trying not to create a all-new gun system. And why wouldn't it work? Please explain, so I can develop this concept.

 

[Armedsask]

If it accepts an AR15 upper, it's an AR15 variant. Restricted.

It's been done already, ACE had a prototype done up. However, if you use a factory AR15 lower, it will be a prohibited bullpup stock.

I will now stop looking at this thread because it's probably going to make me go nuts.

 

[cadgo]

You can't have it both ways, either it has nothing to do with an AR-15 and its non-restricted or it is an AR-15 variant and it is always restricted.

 

[Wantabe_ Warrior]

If the receivers were stretched so that they couldn't be used with AR-15/AR-10 receivers, would there be a chance of unrestriction? Or because the upper looks like an AR-15 upper it's automatically restricted?

Sorry if I'm beating a dead horse here, but this idea has thoroughly imbedded itself in my mind. And, to me, an AR-15 inspired/based rifle gives it the largest aftermarket support.

 

[Stevebot-7]

Are you utilizing any 3D software for this? If not I suggest Google SketchUp, it's free and it works rather well with precise and objective measurements. Though it does get kinda picky below the 1/16" scale, and generally has fits at around the 1/64" so it's not idea truly precise models, and it has hesitations about organic shapes, but it's certainly enough to get a decent model worked out.

This is one of the projects I've been working on, haven't done much lately I've been getting distracted with other stuff, but you can do some impressive stuff with SketchUp if you have patience. If you want some help developing the model I'd be willing to offer my services.

I'd say with some careful designing you could get a NR bullpup design that is compatible with AR grips, stocks, rails/foregrips, triggers and mags, but you would need to do it carefully and in such a fashion that your upper cannot function with an AR lower and your lower cannot function with an AR upper. Function in any sense of the word, even if it only works once and causes the thing to explode.

 

[Wantabe_ Warrior]

Stevebot-7, thank you for the offer, and for pointing out StetchUp for me. at the very least I might be able to get a basic (2D) idea from my head onto something other people can see.

 

[TRich]

I would jump on this concept, but unfortunately as it has been pointed out I don't think it is a good work around. It would be restricted due to the AR-15 upper and if you have to modify the upper to fit then it negates the concept all together. I think building a NR bull pup from the ground up would be a more viable option than one based off of the AR-15 platform.