I am working on a project that actually started on the Proffesional Ordinance board. The goal is to put an AR type rifle into a P-90 stock bull-pup configuration. The problem is the buffer tube. I have some  ideas but need some advice any help would be greatly appreciated. Please E-mail me and I will tell you all about it.

Sorry, guy. I'm an ELECTRICAL engineer.  I'm looking for help on a fusion-powered magnetic induction railgun [rail]

I'm no expert but...

Since you haven't stated what the problem with the buffer pad is, so I will guess you want to reduce the buffer pad length.  Find/design a variable force spring equivalent to the current spring requirements, except shorter.



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Why don't you check out the original OA93 AR15 pistol manufactured by OlyArms. That should give you some ideas.

Michael

Well KBaker I'm an EE major at the University of Akron, if you ever get funding for the design give me a call especially if I can use the prototype after its completed.

Well I dunno how much help I can be. I am a software engineer so unless the gun is software based...

Dan

Sounds like you're going to have to do a major redesign along the lines of the ZM Weapons rifle. You can't shorten the buffer tube too much because, well, the buffer has to have room for the gun to cycle. Therefore it seems to me you would have to do away with the buffer and spring, which means a major redesign of the upper, bolt, carrier, etc.

Of course, as an EE, what do I know....

The big problem is the length. Here is what I was thinking. let me know if you think it would work. Model 1 sales pistol buffer tube is 4.5 inches long. I would need one 2 inches long. What if I cut 2.5 inches off the bolt carrier and shorten the model 1 sales tube to 2 inches. buy looking at my ar buy cutting the carrier it would not interfear with the hammer. what do you think???

I agree the length is going to be your biggest problem. 2" for a buffer tube.... If you shorten the carrier, the buffer will extend out into the upper receiver - not good. Also, when you shorten the carrier, you will have removed weight which will have to be accounted for elsewhere, like with a lower tension spring. Without being a mechanical engineer, you will be taking your chances on guessing the correct spring tension. You will also have to choose a spring with the right extended length and pressure at extension, as well as not being too long as to cause binding from the spring stacking up when it's fully compressed. My big concern is we still have the buffer hanging out into the upper receiver. I still think you will have to eliminate the buffer completely, redesign the carrier and upper receiver to use a different carrier spring arrangement. We haven't even begun to consider the gas system yet either. You will end up with so much work and expense in the modifications, you may be able to just go buy the ZM unit cheaper.

I do not recommend that you shorten the buffer tube. The AR design as it stands has minimum "overtravel" As the bolt ejects there is marginal enough space for the bolt to move.

In an AK47 you have plenty of overtravel aiding in its reliability and slowing its full auto rate.

In addition a reduction in mass will result in higher bolt velocity (>impact) not a good thing, if you shorten the spring compression (shorter buffer) the resultant stress on the spring will result in less reliability/life.

Recommendation: take a good look at a paratrooper FN FAL. In the Fal the buffer springs runs through the stock (wonder where Stoner was looking). In the paratrooper variation the recoil ssprings runs above the bolt carrier in a special bolt cover.