This started in Ed Hubel's 12gaFH thread, but I'm starting a separate thread here since it's a specific rifle build instead of discussion about his 12gaFH cartridge.
Ed's thread: http://www.gunco.net/forums/f113/12g...l?=#post591946
I've liked the Maadi-Griffin ever since I first saw a picture. It's a bullpup .50 BMG. The company sold them as complete rifles, kits, or plans. None of the above are still available, but acquired the plans from a web torrent. The scan was poor but readable.
Basically, you need 7" of 2" diameter 4140, 5" of 1-1/2" diameter 4350, a few feet of square and round tubing, some music wire, a bit of flat stock, and a few odds and ends from the scrap box. I figure the metal would run under $100 even if you had to buy it from Aircraft Spruce or Online Metals.
Unfortunately, the ex-military .50 barrels have gone from $50-ish to $300-ish, and though I looked at the plans from time to time, I have other projects that need my discretionary entertainment funds more.
The Voices told me if a Maadi is .50 was cool, a Maadi in 12gaFH would be even cooler. I laughed at them in derision.
I just won a rifled 12 guage barrel blank, 27.5" long, from Gunbroker, for $129.
Looks like the Voices got the last laugh.
I don't remember where I got the pictures, but these are completed Maadi-Griffins. One builder chose not to use the AUG-ish handguard, but the guard is correct for the Maadi design. The bottom picture is from the cover of the plan book.
Yes, that's the bolt handle by the buttpad. The buttpad is attached to the end of the bolt, and they both come out of the receiver together, with the fired cartridge held by the extractor. You clip another cartridge on, then twist the buttpad back into place.
The basic design is adaptable to a more conventional layout by moving the bolt forward and providing some space for it to move, but then you increase the length of the rifle.