I only load 38/357 as well as 270s but, the thing that strikes me about your original post and then your followup is that you are using magnum cases and special load data. Moxie points out that you should bump it up to 8.5 and you come back with your data that shows a top of 8.0. Again, you are basing this on 44 Special data. If you are looking for a light load for the Mag then use the data for the mag and not the special. You have a 0.125 difference in the case length which will change things. Volume, bullet depth in the case, etc.