Interesting idea for a bullpup rifle

When asked what “bullpup” I generally tell people “it is a rifle where the magazine sits behind the trigger”. Rabbityrabbit came up with an idea for a bullpup where the chamber is behind the trigger, but the magazine is in the same place as it is on a non-bullpup rifle. The design idea was inspired from the Boberg XR9 pistol.

While I think this idea could work well, many armed forces do fine with a standard configuration bullpup.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Crystal

    This seems to be a lot of extra moving parts. Not sure that’s such a good idea in the Armed Forces but that looks like a pretty sweet idea! would’ve never thought of it.

    • Crystal, I would have have thought of it either!

  • Puke

    Seems awfully complicated to me as well.

  • EzGoingKev

    While I agree about the moving parts comment, I still like it.

    I like the bullpup design as it gives you a long barrel without having the length in front of you. Having the mag out front makes mag changes much easier.

  • dogon1013

    Increasing the distance between the magazine and chamber just increases the distance and time for something to go wrong.

    I can just imagine a short-stroke situation where the round that was just pulled out of the magazine gets pushed back, but not far enough, and then the round returns forward towards the magazine. This would mean the tip of one round slams into the primer of the next round in the mag….not good.

    it is interesting though, and does offer a solution to those who don’t like the magazine in back.

  • Cymond

    I love bullpups, but I wonder how long it would take an actual working gun to go through that cycle time. I’m guessing it would be rather long. I’m curious what the rate of fire would be in a full-auto version.

  • Carl

    This gun will be expensive, heavy and complicated compared to a standard bullpup. Is having the magazine aft of the grip really such a tremendous problem?
    It’s very nicely modeled though.

  • Carl

    I also wonder whether the designer has done any calculations on the velocity of the cartridge carrier. That is a very long way to travel back and forth at 600 rpm or so…

  • pavuk

    This system could solve problem with hi-cap magazines, but i think it will never been used in military rifle.

    I think that one of problems (except that delivery system) of this system is low fire rate. I think that it’s impossible to make this with fire rate higher then 400rpm.

  • MrTolliver

    A very interesting concept, but the distance the round has to travel is probably too much for it to be reliable. The Kel Tek RFB and the FN FS2000 both have forward ejection but they have their magazines in the rear which increases reliability. This probably could work if the firearm was constructed very precisely maybe a high end hunting rifle? 🙂

  • R.A.W.

    “I also wonder whether the designer has done any calculations on the velocity of the cartridge carrier. That is a very long way to travel back and forth at 600 rpm or so…”

    Yeah. Those bullets had better be crimped in there real good.

  • Tango_Delta

    Interesting design but it won’t be able to achieve anywhere near the rate of fire demanded by operators in the military and just from looking at it, nowhere NEAR the reliability soldiers demand and need. The whole ejection tube and loading into the bore operation looks like a clusterfuck waiting to happen.

    Still very interesting, the benefits of a bullpup can’t be overlooked. They’re inherently lighter and tighter and pack more of a punch, they’re more bang for your buck practically speaking. It just feels awkward having to reach under your armpit to load the magazine and can easily turn into a more time consuming, two handed operation. I much prefer loading a mag that’s in front of the trigger group, where I can see it. I’d like to see someone make this work reliably.

  • The Doc gives it a negative.

    1 – The rod that the cartridge picker (to borrow a term from tape library robotics) runs on is very thin. At the speed and force (see 2) that the picker would have to run, it’ll lose tolerance very quickly, and will probably suffer from whipping or distortion long before that.

    2 – To maintain force over that much distance is going to require one hell of a spring, and to get the picker to move that far with enough free energy is going to take one hell of a gas system prime for clogging. Big tubes will be easy to clean though, except for the multiple ports for multiple services.

    3 – It appears that the cartridge rim is slid out of the picker and up into the bolt in an “uncontrolled” manner. That’s left to final design though… but if a cartridge were to get loose, this thing may end up an absolute nightmare to clear, especially if you get one between the picker and the bolt.

    4 – This sucker’s gonna porpoise like a dolphin. (har). Picker’s impulse is way, way out of phase with the recoil instant AND changes mass.

    *looks closely and determines that the picker is actually blown back from the resting spot and “knocks” the locking block up (SVT-40 tokarev issues, blocks break under rifle pressures btw) and the bolt back, which leads to*

    !!!!5!!!!! – It appears that if spring pressure returns the picker, then if the lifter breaks or mistimes or by other means the cartridge remains in the picker for the return stroke…. THE NOSE OF THE BULLET WILL STRIKE THE PRIMER OF THE NEXT ROUND IN THE MAGAZINE. That’s decidedly uncool.

    It’s an awesome idea, terrific first look but man are there some flaws.

    If you want a rear-chambered bullpup with an easier access magazine, why not adapt the Calico helical top-mount magazine in a PS-90 style layout? To “fix” this design you’d need to put the picker on rails in the reciever, maybe use a constant-tension style spring… I’d adapt the block to take a role in accepting the cartridge rim as well for better control, and I’d also be forced to put some kind of magazine interrupter in there to hold the next cartridge in the magazine down until the picker is past the point where there’d be room for a cartridge between it and the tail of the next cartridge.

    One other quibble; if the gas impulse blows the picker back, then you’ve got a long hang time with the cartridge in the chamber before the picker returns. If the gun gets too hot and cooks one before the picker returns, the gun’s going to come to a halt because the pressure will either prevent the picker from returning with enough force to grab the rim, or cycle it completely with no cartridge mounted.

    For that matter, there’s going to be a lot of control mechanisms running the span of the receiver, because the firing mechanism is going to have to be disrupted until the picker reaches the magazine.

    Again, it’s beautiful work and an elegant illustration, but the ancillaries slaughter it.

  • There was a Czech design called the KRASA that used a similar concept. Some belt-fed machineguns, particularly those designed for rimmed cartridges, work along the same idea since they have to pull the cartridge backwards out of the belt.

  • Jim

    This looks like a “solution” looking for a problem.

  • Adding to the idea, it appears that AAI’s LSAT carbine design is pushing cartridges backwards out of the magazine directly into the chamber aligned behind it. The chamber is separate from the barrel, swinging from a loading position to a firing position. Since the cartridges are completely cylindrical, it really doesn’t matter which end of the chamber they feed into. When it enters the chamber, the new cartridge pushes out the empty case.

  • Ben

    Hi, I’ve been lurking on the firearm blog and have finally decided to comment. New bullpup actions are of special interest to me as I have been trying to reverse engineer the russian TKB-022 prototype rifles. I am ignoring the obvious missing pieces, such as the mechanism raising the spent casing into the ejection tube, because this is, after all, a concept mock up. Still, the biggest problem I see is the inability to use standard Stanag or AK magazines because the cartridge moves backward, not forward. The necessary proprietary magazine might also be unreliable because the top cartridge is in no way incased from one side, unlike the current mags. This limits the action to belt, which has been cited as another disadvantage of a normal bullpup. As for questions on there being too many moving parts, this action is simply a automatic version of a pump shotgun with out the tube magazine.