I am no metals engineer but I can't see a problem with a monoblock, given that you would be essentially surrounding the barrel with good grade steel. Secondly, the question would be what cartridge are you planning on? Assuming you stay with a low or medium intensity round as recommended by Brown. I think part of the selection goes to the machining aspect....and/or your ability to work the stuff. 4140, while tough, is not that bad to file. A shoe lump construction, might be another matter. Maybe some experienced folks will jump in here, kind of goes to my first post.