I've had this idea rolling around since before SPE where I showed off an almost complete prototype. Since then I've milled the sear slot and on/off hole in the CF tube and have test cycled it about 1000 times with no problems (except the occasional chuff from my trigger finger getting tired).
I wanted to see what the interest may be in a Carbon Fiber mag body. Well, it has an aluminum breech and a CF tube attached. The prototype breech was from a ULE body that Shane-O unknowingly donated and some sample CF tube I purchased from a supplier. Right now the tube is has just a slight interference fit with the breech so its easy to take apart and clean. That may change in the final version, but for now the slip-fit seems to be working nicely.
Anyway, below are some pics of the prototype as I tested it and some shots of the body itself. Below that are some screenshots of a breech design I've been working on. If you have any input on the design that'd be great. I am also considering designing up a rail to match the body, but that has yet to be seen. If there's enough interested I'd definitely like to do a run of these bodies. Since there's less machining involved than a usual billet aluminum mag body, the price will probably be slightly lower, but I don't have any specifics at the moment. I'm kind of leery to do a pre-order as those usually turn out long over-schedule, but if I get a solid quote and lead time from my machinist for the bodies, it may be safest for all involved. Oh, also the tube is available in textured gloss or satin sanded (pictured) finish. I thought the sanded satin finish would go nicely with a dusted breech section.
Let me know what you think!
The only thing that may concern me is the wear on the inside of the CF tube from the stainless steel bolt sliding against it. The pic shows the internal finish on the tube. Most of the scratches were there when I got the tube in the mail. I attributed this to the manufacturing process of the tube when they slid it off the mandrel. For the prototype I put some light lubricating oil all around the inside of the tube and a thin coat on the bolt before I proceeded with testing. After about 1000 cycles the tube didn't show any significant signs of wear. I know 1000 cycles is a drop in the bucket, so I'll probably need someone with pneumag or RT guts to cycle a scuba tank worth of air through it so we can get a better idea. The good thing about the modular design is that the CF tube is easily replaceable if it does wear out prematurely. And the tube is relatively inexpensive for short sections like is used here.
Here's the breech design I had in mind. The computed weight (theoretical) puts it at lighter than a ULE body (I forget by how much). The prototype body pictured above is 105.5g (3.73 oz) with the feedneck and detent installed and 72.3g (2.55 oz) with the feedneck removed. This design will be slightly lighter than that because of the material removal around the feedneck. I may increase the amount of material there for strength reasons, but thats the overall design flow I wanted to go with - simple yet aesthetically pleasing. Right now I have it designed for 'Cocker barrel threads, Angel feed necks and Angel detents.
And a cross-section view:
Thats all for now and please let me know what you all think. I'd love to do some more projects for the AGD community.