I've made a little progress, and I now have the muzzle done. I plugged the end of the barrel with 2" of epoxy mixed with lots of carbon fiber, and then bored it to accept a round muzzle end. That made it easy for me to machine a good, tight tolerance fit . You can see that I stole a page from Dan and Don Paul's guns with the way that I tapered the rear of the band slot.
That sucks Hau. Best wishes for a speedy recovery.
I wonder if some sort of support belt would help? Probably kill your breath hold though.
It also depends on the gun being loaded. It takes lots of stretch to get the butt of a 72" gun to position 2. Loading guns with lots of bands repeatedly isn't fun without good padding.
3 to 6. I see no reason to make the loading pad small. A pad that is too small and too high is a sore spot with me. There are many suits and rash guards on the market which I will not even consider because of the size/placement of their loading pads.
Good job thinking it through carefully Dan.
BTW, I really like the lining in my Picasso wetsuit. Makes for easy entry and exit and I use my 3mil all winter long in some pretty cold water. Riffe also uses a similar liner in their new suits, something you might want to consider.
I shot it with my little 2 band 52" inside the rig reel gun. By far the ugliest gun I own, but probably the one that sees the most use.
I'll try to find some more current camp pictures. It is basically done.
. . . did you have a chance to shoot your hybrid
Only in the pool so far. I wanted to test it on the smaller AJ's on the Gulf wrecks off Pensacola this Fall, but they closed the season unexpectedly not long after I finished the gun. :angry5:
It's hard for me to say, because I just haven't shot as many different guns as most of the guys here. Maybe it's all in my head, but the two guns that I have built with high mount handles seem to kick straight back, with little or no muzzle jump. And one of those two guns is my hybrid, which doesn't really have mass on it's side compared to a heavier gun.
Hopefully Griswold will add his observations. He has far more experience shooting much more powerful guns. But if you look at most of his later creations, they have the high mount handle too.
Edit - Just saw your second post. I added it up, and the carbon fiber sleeves and fabric for this gun totalled about $95. Add in epoxy, brushes, etc. and it's probably more like $120. Still, that's really not bad compared to a similarly sized teak stock.
It's one of the old PoseidonSub mechs by Steve Verso. I think the same rivet would work with any of the mainline mechs, as the top housing thicknesses are reasonably close, and the rivet is pretty elastic.
Dan - My approach wasn't very scientific, and may not be optimal. I just positioned the trigger internals on the outside of the mechanism housing, and picked a spot that was near the tip of the sear, but not quite at the very tip where it engages the trigger.
I checked it with two different shafts, a Riffe and a Ray Odor. Both release cleanly, with no apparent interference from the silencer. There is a detectable double click when the shaft is loaded. With the Riffe shaft, it is barely noticeable, and you probably wouldn't notice the difference if you did not know the silencer was there. With the Odor shaft, you can feel two clicks as the shaft is loaded. I'm not sure what the first is, but it is the second click that indicates the mech is cocked.
I didn't take any measurements, but visually, I notice that the end of the Odor shaft has a substantial chamfer, whereas the Riffe is square cut.
Edit - I just compared it to an unmodified Neptonics mech, and noted the same double click with the Odor shaft. So there does not appear to be any difference in either loading or firing due to the silencer.
I really don't know if a trigger silencer has any real advantage. But if you want to give it a try, I don't think that you will find anything easier than this.
I found these EPDM rubber rivets at http://www.sidewindercomputers.com/setof4fanrid.html They appear to be used as fasteners / vibration isolators for computer cooling fans. Anyway, the shape is perfect for installing in the top of a trigger mech to cushion the sear from making the sharp metallic contact with the top of the mech when fired.
Here are the rubber rivets:
They couldn't be any easier to install. A 9/64" hole in the top of the mech is a snug fit. Then cut off the bottom half of the rivet, and pull the thin top of the rivet through the mech, from the inside out. Then trim the remainder. Done. The mech is almost dead silent on the benchtop. Just a dull, cushioned "bump" when fired. I have no idea how well they will hold up long term, but at $1.75 plus postage for 4, they are cheap and easy to replace.
So Tin Man / Grizwold, am I right in thinking that anyone who won the FRA raffle or auction could be the proud owner of this gun or one like it to their specs?
Yup. 
I was hoping to have a completed gun to show off before the raffle ends on December 18th. I may not be done by then, but I wanted to at least post some progress pics to get the creative juices flowing in anyone who still hasn't bought their tickets.
You da man!! That thing is saweeeet!
amazing...and along those lines...couldnt you move freely between the round profile and the flat bottom only on the places where it was needed (ie just where the clamps go and just for the handle?) the benefit of the wax being that it doesnt have to be pulled out...just a thought
Yup. No reason why that wouldn't be possible. The process is mostly limited by whatever tools you have available to shape the wax core.
Would it be possible to make the carbon tube more rounded on the bottom same as the top? Bring it down in overall diameter a little?
Certainly. The current shape was really driven by only three factors, and they are flexible:
1. I kept the bottom relatively flat, so that the handle attachment could be a simple "screwed plate" design similar to a typical handle. But this really applies only in the handle area. An if you wanted to go with a mortised handle, as you have done before, then the bottom could certainly be more rounded.
2. I didn't show pics, but there is an intermediate step where I clamp it from top and bottom to push a Delrin "dummy" piece down from the top to force the carbon fiber down into the track recess. I learned from the tube on my hybrid that clamping from above will tend to produce a slight flat spot on the bottom of a fully rounded shape. But the flat area is only 1/4" to 3/8" wide, so the bottom could certainly be more rounded then I made it in this case.
3. Squarish sides and bottom make it a little easier to hold the wax in a vise repeatably when cutting the wax "ingot" to the final shape. But again, only a small flat spot is really required.
I did calculations before I started to make sure that this gun would balance well with a 5/16" shaft, 10" of overhang, and a full 1/8" wall thickness. I think it would certainly be possible to make the tube a little smaller, especially if intended primarily for a 9/32" shaft. And 3/32" would probably be plenty of wall thickness.
It was pretty heavy with the wax in. I didn't check it, but I think it would have been seriously negative, even without the shaft.
Here's a couple more pictures for a size comparison. The barrel on the left is a typical 28mm barrel, and the one on the right is a 30mm barrel.
That's where the raised handle will be, to get the grip as much in line with the shaft as possible
The finished barrel is still a little long, so that I can trim both the muzzle and butt ends to their final dimensions. It's about 1-7/16" square, with a wall that is just under 1/8" thick, and an enclosed track cut for a 5/16" shaft. My hope is that it will be very maneuverable and easy to swim with, like a euro, but with an 8" butt extension for hip loading. The high mount handle area will get the modified Neptonics trigger that I posted a while back.
And strong?
Of course, once the carbon fiber is molded around the wax core, you have to get the wax out. So here's how I finally approached it. I used a $7 piece of stove pipe from Home Depot, and cut a plywood circle to plug each end. The plywood circles also supported the gun so that it wasn't touching the heated stove pipe. A small slot in one of the plywood discs allows melted wax to drain.
And here's the elaborate setup . . .
A thermometer in the uphill end allowed me to keep the temperature at about 160°F. Plenty hot enough to melt the wax, but no danger to the cured carbon fiber or teak inside.
Success!
Next, a few shots of the finished barrel . . .
