Six hour canoes and chamber inserts.

Recently the book "Building the Six Hour Canoe" arrived at my local library. As promised I checked it out. It seems to be a viable project, however the instructions call for 4x16 sheets of marine plywood, not your average home center stuff. There is instructions on how to use 2 4x8 sheets with a seem in the middle. Also the completed canoe has a strict load limit of 250lbs. The 250lb weight limit rules out this project for me. I'm in the mid 240's on a good day and don't have room for something that can't at least carry one of my daughters with me. I also doubt the six hours in the title. A week of 2-3 hour sessions would probably be more like it. And I consider myself a moderately fast wood worker. The $65.00 project gun is in semi limbo until after either I buy supplies at this weekends gun show, or my Gun Parts Corp order arrives. I have already owned a 2.5" 410 adapter for 12 gage chambers. I have never used it due to 2.5" 410's costing twice what 12 ga shells cost. I may one of these days come accross some cheap 410's. Or I may get around to converting my stash of .444 marlin brass into brass 410's. Until then it will probably remain unfired. I did two weeks ago order a 12 ga to 9mm converter on ebay. It arrived within a few days. Made from aluminum by an outfit called Dina Arms. I was skeptical at first. Reviews I could find on the web weren't promising. Most claimed extreme inaccuracy. Because this project is meant to show that a practical survival gun could be built on a budget I ordered one anyways. Yesterday I grabbed a partial box of cast bullet mystery reloads. The thing functioned as promised, and at first the reviews seemed right about accuracy. First ten rounds were minute of garbage can lid at 25 yards. Shooting at a 3x5 index card with no markings everything went into a 12" area starting about 3" above the target. On the 11th shot I hit the target almost dead center. Carefully I opened the gun and noted that the 9mm stamping on the converters head faced down. This time I carefully reloaded the insert into the gun and made sure it went in exactly in the position it came out. This shot cut the edge of the previous one, the next two shots brought the group up to 2". I should add at this point it was raining a steady drizzle and my glasses were getting foggy. This calls for more tinkering. I am watching wear on the inserts rifling. I have a ton of cast bullet reloads to shoot, I am very skeptical about shooting jacketed ammo. Copper is much harder than aluminum and I suspect the adapter would wear out quite quickly. One other thing, I expected the report to be less due to the length of the shotguns barrel, it was actually quite loud. And, you'd be amazed at the amount of crud that goes out the end of a pistol barrel and stays in the shotgun barrel. In a few weeks I will order an all steel adapter from MCA and see how it shoots. I'm leaning towards a 32 H&R magnum adapter this time. I have a bunch of 32 S&W and 32 Longs kicking around. The other option might be .30 carbine, I have several hundred rounds of those. The other idea I'm toying with is .311 round balls meant for my muzzleloader thumb pressed into any of the above casings over a bunch of black powder. I've also considered and ruled out 30/30 or 45/70 adapters. I am leary of pushing the pressure in my guns frame as I'm pretty sure it's ductile iron like most cheap shotguns. Woods