I have a Model 54J that is a 1-14" twist chambered in S & H. What is the longest bullet this twist and chambering will shoot. So far I cannot make 139 Gn bullets work and the way I calculate it I cannot get a good number with 120 Gn either at 1.236" in length for the 120 tipped Barnes. Am I limited to a V-max 120 or something shorter? Thanks for the help in advance & God bless.