Re: 1.20"shank vs 1.25" shank
Shank? generally that relates to major diameter of thread tennon, but I reckon you mean the OD of the barrel ahead of receiver. 50 thou is a little less weight. Depends what your stock was inletted for, could mean a little more room. Strength, rigidity, not impacted hugely by the smaller diameter. Sometimes the 'shank' diameter is determined by the original bar stock diameter used in making the barrel..Leaves enough to clean up any run out..