ivans,
That is pretty much the way one would be fit by a factory. Get a base made for soldering onto rifle barrels( ERA, or EAW should have them) and using your favorite spotting compound, scrape the bottom of the base to closely fit the barrel. Wire the base to the barrels using soft iron( "tie") wire, with flux/solder between them, with what ever masking( soapstone, chalk etc) you normally use to lessen cleanup. Most importantly, wire up the barrels, ahead of and behind the base, with rods/wedges to prevent the ribs from coming loose. If you do this prep work and use ordinary care, you should be OK.
Mike
