Fuzz I just figured out why it mostly goes the otherway. This is to keep from wrapping around the speartip. The way I built this does take longer to load but b/c it's a short gun w/ little overhang I hadn't even thought about it being a negative this way until now. Maybe I'll switch it later (nice part about fiberglass).
Besides the muzzle and wings I also:
*Filled the barrel w/ epoxy and foam to add balast. The total weight is now 4 1/4 pounds w/ the custom 7mm hawaiian shaft. This gun sinks always, like the spearfishing specialties low-vis. gun (padauk (sp?) or some wood). Kind of a safety feature in low vis and I always use a floatline so not a problem.
*Placed a rubber snubber on the trigger to keep the sear from hitting the trigger after release. Yes this is based on the JBL 'silencer package':duh , but it does actually reduce the sound. I also added a section of rubber tubing inside of the line release spring. This stops it from slamming into the al. handle on release and also quiets the opperation. The final internal change was to add tubing and silicon over the metal stoper for the line release on the opposite handle half (I have a photo of all this if anyone wants, but it's kind of boring). Actually had to build a new trigger spring from an old bass spinner after a mishap while cleaning. It will work if you've had a similar problem.
*The home made shaft is recycled from an old jbl super carbine shaft and drilled to eliminate the slide ring all together. This even worked w/ the closed original muzzle although I did reduce the size of the length of the opening to limit friction. The blank section was filled down and a 3" flopper was added. The band slots were also moved further back and closer together than stock shaft, thus increasing band stretch.
* The loading stock was completely filled w/ epoxy to help balance the gun and off set the muzzle weight. A small drainhole was also drilled in the plastic loading butt to facilitate removal.
*The 5/8" bands are 13" and 14" and have loops whipped into the ends. These dyneema loops have another stretch of dyneema tied imbetween. This was all from shadowkiller's post at adrenaline and it works great. Allows me to switch the wishbone at slightest sign of fatigue.
*An extra dyneema wishbone is tied to the floatline attachment which is a beefed up 1/4"(or so) ss eyebolt inserted through the existing hole at the bottom of the handle. This lanyard has a rubber 0-ring/trim-ring/gun handle/flat washer/nut/locking nut sandwich which keeps it quiet while allowing it to rotate the bold is also bent over and ground to make sure it won't slip. This connection is also very strong as some of you may recall I got towed behind a shark with this setup and the weight on the lanyard as my floatline was being pulled.
*In the absence of the slide ring the drag-prone polyproplyene shooting line was changed out for four hundred pound black monofilament crimped w/ heatshrink tubing over the connections (Note: This does not go cleanly through the stock muzzle, but a bare crimp w/ 400# will). A bungie was also made from 3/8" tubing w/ 350# spectra core.
*The barrel got covered w/ three passes of 2" wide electrical tape. 3" will cover w/ two lengths, but I can't find anymore.
Guys I'd be happy to answer questions for you on how to play around w/ that old JBL. It might not be pretty buts it fun and it now is surprisingly quiet and when fired the recoil is straight back, not going into muzzle kick-up.