I have a chance to pick up a Mauser commercial action and I would like to have it built with three barrels, I was thinking of using a barrel nut like Savage uses. I have seen one with two barrels before it was shooting sub 1/2 inch groups with both barrels. But the price tag was very hefty. I talked to several smiths and they are talking about $1000 to $1500 for the work. I'm only going to have the money once to fliter away so I'm looking for help on picking calibers, something for varmints, and deer and something for elk and black bear, and something for long range target. right now I'm thinking 243AI, 308, 6.5X284.