Bob,
First of all, Stephen Howell did(does) fantastic work and I am not denigrating it at all, but I believe you will find it much easier to make a Monoblock instead of shoe lump type block. The obvious difference between the two types is that with a Monoblock, the barrels are inserted into the Monoblock and the "joint is large enough that soft solder is sufficient to hold them, avoiding the possibility of overheating the barrels. The often-voiced objection is that there is sometimes a visible joint, but not everyone finds this objectionable. If you can remove the hinge pin, and locking blocks, the receiver will tell you the dimensions you need to mill the Monoblock. I believe barrel blanks already prepared for use with a Monoblock are available as a special order from Walther. The diameter of the holes in the Monoblock should be determined from the end of the barrel blank.
Mike
