Sand the "inside" grip surface of both shells flat using the lines of the knurling as a guide. It looked like I was hitting the middle 2 lines of knurling when I started. I tried to leave a little more plastic on the shell than I thought was necessary for strength. Sand the inside screw bosses too as indicated by the yellow line. I used a clean toothbrush (no grease), then a soft brass wire brush to get the dust out of the knurling. Then I went over it with alcohol.
I put a small drop of fast superglue on one side and then placed the shells next to each other on a flat surface, plunger tubes down. Then I carefully brought them together, matching the lines of the knurling and looking down the sides of the barrels for straightness. If it doesn't line up right now, just pull it apart, adjust the surfaces and try again. I let it dry for a few minutes and then found a few spots where capillary action would really get the glue into the gaps. Try to go slow and hold it at different angles to flow the glue around. Be mindful of the plunger tubes. (Note: glue it up when the shells are empty)
If it's a tiny bit off now you can try to spread or clamp the barrels and glue strategically. It's best to overcompensate with your corrections. Once it's ok set it aside to dry once again making sure the glue is not going to go places it shouldn't. I added a second layer of glue as that seems to really keep stuff together.
Sand down the "inside back" 2 screw things like this. One on each side. Not all 4. Test fit this and make sure you've removed enough material or it could cock the barrels when tightened.
Done. You can easily link the triggers. It is chunky as hell in the hand, but some improvements can be made here later. I'd recommend trying these taped together or something before doing this to see if it'll work for you.
I tried linking the priming bars through the holes already there. I used a nail with the head cut off slipped across the priming handles. It was better for priming but the span across the triggers made getting off both shots at the same time impossible. Something linking the triggers might fix that issue and be pretty cool. I found that just differences in the speed of the plungers were too great to include it in the writeup. Firing them singly was of course right out.
"Here's an idea. Put a long screw with a nut through both of the priming rods so you could prime them both at the same time. Taking the screw and bolt out during a war could let you use a simultaneous double shot or two single shot."
And Y-Brik :
"Try disabling one of the triggers- keep it constantly pulled back (zip-tie) or clear off the catch notch (the 'nail'). If the priming bars are linked, one catch may just be enough."
"I want to do this with, like, twenty of them, and link the triggers with a steel bar going across all of them."
I will update this post with any new information about this mod. Please post or pm any ideas you have. I will respond to questions both in the original post and in the thread (to let you know I responded). I will edit in answers and credits as needed to de-clutter the original post.
This might work for you. It's pretty but utilitarian. Or pretty utilitarian. Write-up to follow.
Edited by iamthatcat, 28 November 2011 - 02:23 AM.