If you want to hide the seam where the mono block and the barrels meat then undercut the shoulder on the barrels a bit and chamfer the front of the mono block. When you crank the barrels into the mono block use enough force to cause the edges of the undercuts to raise up a bit. One trick is to turn the barrels in, back them off and crank them in again. Keep doing this enough to raise the sharp edges of the chamfer and undercut then solder them up again using enough force to raise the "lip" of the edges. DO NOT use too much force as you do not want to tweek any thing. If done correctly and polished out well no seam will be visable even with a magnifer, give it a try.
Please forgive my stupidity but what is a shoe lump? I truely do not know please explaine.