The Hodgdon manual states that the 350 Hornady bullet can be loaded up to 60 gr of 3031 in the .45-70 with about 35 KSI chamber pressure. You are at 80% of maximum load (48 vs. 60 grs.) which with a canistered powder may be too low a loading density. Sometimes pressure is higher with too low a density of cannistered powders. Try using 4198 if you want to load slower loads.
