Was thumbing through my Speer No 11 this morning and noticed that for the 257 Roberts they have different data for their 100gr flat based and boattail bullets. In some cases, the boattail data shows a full grain greater charge and over 100fps less velocity. I don't recall seeing this discrepancy in any other load manual and it doesn't show up in any other manual that I have on hand. Seems counter intuitive since the boattail should have less bore bearing surface. Any ideas?
