TomN,
Oh, I understand, you are talking about the shotgun shell rim cut in barrels, that needs to be bushed for rifle conversion. Yes, you can ignore installing the bushings, and bore the barrels out beyond the rim cuts (I have done it myself a few times), BUT BE SURE THAT WHEN DOING SO, IT LEAVES ENOUGH METAL AT THE TAPERED END OF MONOBLOCK (MUZZLE END), ESPECIALLY IF YOU WILL BE THREADING IT FOR INSTALLATION OF NEW BARRELS. THREADING ISN'T ALWAYS NECESSARY; ONE CAN JUST SOLDER FULL LENGTH INTO MONOBLOCK, WITH NO THREADS---THEY MUST BE SOLDERED PROPERLY AND WELL, THOUGH, OF COURSE.

Rhodes,
On Ellis Brown's first double rifle conversion, he used a 16 gauge common German action, but I can't recall which make. I am sure that I have that information in my notes, but it would take me forever to find it---he may have mentioned the make in his book too. However, the make isn't important, as he has used a number of different German made shotgun actions for conversions, as have I, and all of them worked beautifully for conversion. One of my latest is a 1970s vintage Merkel 12 ga. converted to .500/.416 Rigby. Brown used existing barrels to make monoblock on that one, if I recall correctly. He never started using the shoe lump method until well after he wrote his book. I think that in his next edition of the book, he intends a chapter or section in it covering the shoe lump method. One if its main advantages is that it requires no seam between barrels and monoblock. No, I have never shoe lumped anything. The monoblock system is hard to beat, for it makes for a strong sound system, now well proven through many years of use.