theoretically, acetone could cause real problems with the epoxy structurally, it is a pretty badass solvent
I agree it might be a problem if you soaked it for a while. But I always use a quick wipedown with acetone as a cleaner before I apply new carbon fiber over already cured stuff.
Jeff,
out of curiosity, what's the difference in strength from the Delrin to the commercial reinforced plastic ones on all the railguns?
Tough to say, because I don't know exactly what the commercial muzzles are made of. A reasonable guess might be 30% glass filled nylon. In that case, the impact strength, stiffness, and ultimate tensile strength of the glass filled nylon material are about double the values for Delrin.
That is (in part) why I made the muzzle with a stainless wire line anchor, and stainless pin line wrap. By design, I eliminated small protrusions that might be vulnerable to breakage. The rest of the muzzle attempts to compensate for the reduced strength of the delrin material by avoiding major stress concentrations like notches, etc.
Shouldn't be much different. Anybody got a closed muzzle handy that they can measure? the bore that the shaft fires through has to be large enough for the shooting line, so how big?
Cyanoacrylate glues can be removed from the skin with acetone. Would that work to remove blades, or would the acetone damage the blades or foot pockets?
I have never seen clear Delrin, but clear PVC and polycarbonate are available, and have similar properties. I would have to play with some to see how it looks after machining. Clear plastics usually don't look clear where they are cut, because of all the tiny scratches from the cutting tool. But it might be worth a shot.
How invisible would a clear muzzle really be, with bands through it and a shiny spike sticking out the front?
Or do we just want an "ice" muzzle because no one else has one? 
Glad you're happy with it. I'm eager to hear your evaluation when you get a chance to test it, so I can incorporate any suggestions for improvements.
Pretty good idea. If you can mix some fibers, and have them bond well, into the foam you might get some increase in tensile/bending strenght.?
In principal, yes. But the glass fibers also increase the density, which is not generally a good thing if you need a lightweight core to balance out the heavier carbon fiber composite.
What do you mean by keeping it straight?
A long, narrow piece of syntactic block is not as stiff as wood. It needs to be clamped with strongbacks to keep it straight while the epoxy / CF cures. Especially if you are including a built-in Delrin or UHMW track, because the temperature of the curing epoxy will cause the track to grow, which causes the stock to want to bow.
Do you think this can be a way to overcome the warping and aging time associated with wood?
I'm not quite sure I understand what you mean. Are you suggesting wrapping carbon fiber around a wood gun?
Also do you guys vacuum your guns?
No. We use heat shrink tubing. I'm sure that vacuum bagging would be better, but heat shrink is cheap and easy. Same as I did for my hybrid tube.
Sorry. I thought I had posted the pictures of the core for the donated FRA gun.
The donated gun was made from a purchased block.
The temporary piece at the muzzle was attached with a single screw down the centerline. This was only a dummy, so that we could later remove it and be left with an inside void to insert the muzzle.
The large piece at the back was attached with two screws through the ballast holes. The screws were removed after molding the carbon fiber, but the Delrin stays. This is where the trigger mech gets installed.
The reinforcements at the handle and reel were held in place with two small screws, just to keep them from moving while we were laying up the carbon fiber.
Although epoxy doesn't stick very well to Delrin, it would probably hold long enough. Screws are just usually easier.
And UHMW tracks grow at the curing temperature of epoxy . . .
One thing we forgot to mention, if you plan to shape a gun out of this stuff, you MUST make sure you have a way to keep it straight while the carbon fiber is setting up. This is easy enough for simple shapes, but gets challenging for more contoured designs.
Yea, we learned that one the hard way.
I'll have to measure a piece to verify, but the specs say the specific gravity should be about 0.5 g/cc, and it does seem pretty light.
Best I can measure, the density is about 0.59 g/cc. It set up a little harder since this morning. It now carves and sands about like wood, and seems pretty tough.
I tried the syntactic dough (also called "tooling foam") last night. It's a free sample that I got well over a year ago from United Resin Corporation http://www.unitedresincorp.com/casting.htm
It comes as two bags containing moist powders. When mixed and kneaded together, they produced a light, tacky dough. I shaped it into a simple patty and left it out overnight. This morning, it had hardened to about the consistancy of a soft wood. I could cut a piece off with a utility knife, but it took a little effort.
I'll have to measure a piece to verify, but the specs say the specific gravity should be about 0.5 g/cc, and it does seem pretty light.
I can see that it might be useful if you wanted to fill a space where a liquid might cause problems. You could easily pack it inside a hollow handle, for example, without getting any into places where you didn't want it.
Delrin in this case. Sometimes UHMW for other projects.
You're on. Thanks! 
Spike, or no spike?
I would prefer black. When it comes time to extend the gun toward the fish, I'd prefer not highlight that action by having a brightly colored muzzle. I actually prefer muted color gloves for the same reason.
All the muzzles that I have ever seen are black. But most of the plastics that I would use for typical projects are availailable (and usually cheaper) in white. I was just wondering if there would be any advantages, disadvantages, or differences to a white muzzle on a typical rail gun or hybrid?
Would it be easier / harder to distinguish the muzzle against the shadow of a fish? Would aiming be easier / harder?
Would it scare the fish? Or just look stupid?
I didn't remember that we checked it. You know, I just remembered that I have some syntactic dough that we never tried. Wonder if it's still good . . .
If my memory serves me correctly, the lowest density that we were able to get from the Polywood product was about 0.6
Delrin
