Took my 6.5-303Epps out to work up some loads. First set using a 140gr. bullets grouped OK @ about 2 inches high at 100 yds. Next set; 120gr bullets grouped OK BUT the group was between 4 and 6 inches high. Velocity difference was about 500 f/s. Barrel temp not an issue, powder weights all done with a scale and both bullet types are PSP. Would differences in distance to the lands do this as I did not pay any attention to this and loaded both types to the same length. Any ideas as to why such a big difference in POI. Thanks.