Not a lot of progress to show with respect to actual construction. I've gotten two barrels as a start point, but need to find a gunsmith with a lathe to turn my barrels down. I got two 300 win mag Remington 700 barrels for a start. I chose to go this route for several reasons. Remington barrels are readily available at a reasonable cost. They have no extractor cuts and the profiles are done for you. Of course this will mean cutting the chamber end off and rechambering. I'm not aware though, of any large bores. My plan is rechamber for 30-40 Krag, a rimmed, tapered, cartridge ( the bore size in these is .3085). Kind of wanted a venerable old round with lower pressures. I read somewhere shotgun pressures are in the 10,000 lb. range which I guess is why Brown recommends low to medium intensity rounds for shotgun actions. I considered .303 British(bore sizes are all over), Mauser 8 x 57.(Mauser barrels are plentiful, 303's not so much). In a perfect world, I would have liked to have had 2 Ruger 45-70's but got tired of trying to find any at a reasonable cost. Also, I started with 26" in barrels, rather than the more plentiful 24 or 22. By rechambering, I should still wind up at, or about 24". The top pic shows a 30-30 round in the middle for comparison.