I know this has been discussed before but I can't find the thread.
Remember this curiosity? I may actually try to build one of these. Or something based on that action... my SVU clone has me craving another bullpup! :thumbup1:
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The item of interest (for me) is the fact that the only thing behind the chamber is the bolt.
I have thought about this design for some time and I am confident this design could be adapted to any type of rifle. It essentially cuts the bolt away from the carrier and through the use of connecting rods like on a shotgun, or some other type of connecting link, allows you to relocate the bolt carrier, recoil spring, and fire control assembly forward of the chamber. Result: drastically reduced overall size without reducing barrel length (and performance).
The firing pin is relocated and would also use a connecting rod.
The mass of the bolt carrier could be located "around" the barrel in the same way a shotgun action uses "tube" style parts connected by rods. A shotgun-style "around the barrel" recoil spring could be employed, or my preference would be two recoil springs on either side.
The question I have is how much of the bolt mass is "necessary" for the chamber? Let's take an AK for example. Let's say I cut off the bolt right at the point where it sits in the carrier, then find a relocated firing pin solution. I am confident the rifle would safely fire, because the locking lugs are at the bolt face. The mass behind the bolt face lets it sit in the carrier, and the mating surface of the carrier rotates the bolt into battery.
Now to finish the design, you take the part of the bolt carrier that is cut off and it is relocated to the front of the action. The concentric shotgun-style spring I described pushes the bolt carrier forward. Shotgun-style connecting rods connect the "short" bolt to the carrier, and the design is complete.
Ejection would need to be a forward-ejecting style like on the FN-2000 or Kel-Tec .308 Bullup. It could be designed to eject down a "chute" that ejects downwards, and is narrow enough that the spent shells cannot get lodged in the chute sideways. That would handle the ejection path.
The ejector on a normal rifle pushes against the extractor, which make the round flip out sideways. The ejector itself would need to be changed so that it does NOT make the cartridge flip sideways. The best I can think of is that it either ejects at two points, directing the ejection "forward" and not sideways... OR the ejector is shaped differently so that it pushes the round downward, like on an MG42, or even my P-90. The downward ejection would work best, but the magazine is in the way... therefore "downward and to the side" is the best I can figure it would work.
Really those are the only two things I can think of that would be major challenges. That brings me back to my question - how much of the bolt mass is "necessary" for the chamber? I think the answer is "nothing behind the shaft"... thoughts?
ETA: Visio diagram that - I think - accurately describes the configuration of the bolt and carrier:
![Image]()
Remember this curiosity? I may actually try to build one of these. Or something based on that action... my SVU clone has me craving another bullpup! :thumbup1:
The item of interest (for me) is the fact that the only thing behind the chamber is the bolt.
I have thought about this design for some time and I am confident this design could be adapted to any type of rifle. It essentially cuts the bolt away from the carrier and through the use of connecting rods like on a shotgun, or some other type of connecting link, allows you to relocate the bolt carrier, recoil spring, and fire control assembly forward of the chamber. Result: drastically reduced overall size without reducing barrel length (and performance).
The firing pin is relocated and would also use a connecting rod.
The mass of the bolt carrier could be located "around" the barrel in the same way a shotgun action uses "tube" style parts connected by rods. A shotgun-style "around the barrel" recoil spring could be employed, or my preference would be two recoil springs on either side.
The question I have is how much of the bolt mass is "necessary" for the chamber? Let's take an AK for example. Let's say I cut off the bolt right at the point where it sits in the carrier, then find a relocated firing pin solution. I am confident the rifle would safely fire, because the locking lugs are at the bolt face. The mass behind the bolt face lets it sit in the carrier, and the mating surface of the carrier rotates the bolt into battery.
Now to finish the design, you take the part of the bolt carrier that is cut off and it is relocated to the front of the action. The concentric shotgun-style spring I described pushes the bolt carrier forward. Shotgun-style connecting rods connect the "short" bolt to the carrier, and the design is complete.
Ejection would need to be a forward-ejecting style like on the FN-2000 or Kel-Tec .308 Bullup. It could be designed to eject down a "chute" that ejects downwards, and is narrow enough that the spent shells cannot get lodged in the chute sideways. That would handle the ejection path.
The ejector on a normal rifle pushes against the extractor, which make the round flip out sideways. The ejector itself would need to be changed so that it does NOT make the cartridge flip sideways. The best I can think of is that it either ejects at two points, directing the ejection "forward" and not sideways... OR the ejector is shaped differently so that it pushes the round downward, like on an MG42, or even my P-90. The downward ejection would work best, but the magazine is in the way... therefore "downward and to the side" is the best I can figure it would work.
Really those are the only two things I can think of that would be major challenges. That brings me back to my question - how much of the bolt mass is "necessary" for the chamber? I think the answer is "nothing behind the shaft"... thoughts?
ETA: Visio diagram that - I think - accurately describes the configuration of the bolt and carrier:
