Carbon Fiber Gun structures

[PigStikr]

Originally Posted by popgun pete

Interestingly C4 line wrap on the left hand side of the gun, whereas most of my guns line wrap on the right...

That's because it is south of the equator

Turns out the strength/stiffness of CF increases as the 'fiber volume' ie the ratio of fiber to epoxy increases. For wet molding resin infusion gives a high fiber volume. Typically for aerospace prepreg is used and cured in an autoclave - a high temp, high pressure oven. All this is pretty standard tech. I have a homemade vac bag setup for molding that works pretty well. Any wet process needs to take into account removal of the excess epoxy. I use a 'bleeder' for that.
The nice thing about a hollow mold is the pretty finish on the outside 'gelcoat'.
I notice in your gun pics that they are using cloth at about 45 deg. fiber orientation. This is a lot less stiff than axial alignment, but probably impossible to mold axially. Graphite fiber is different from glass or kevlar in that it is really stiff such that it is difficult to make it bend around corners. The weave seems a bit coarse to me though. The really nice feature is the 'no joint' construction where the fibers can wrap the whole circumference. Vac bagged parts are molded in two halves that have to be stuck together. Hence the fibers do not cross the joint leading to a large loss in strength.
Typically carbon is used for it's strength and stiffness to weight ratio. I'm not sure if there are any weight benefits except that ballast could be added in strategic locations to 'balance' the gun optimally. Stiffness can be a nice thing but carbon has very little shock absorbing capability albeit the 45 deg weave helps a bit.