I'm still learning the ins and outs of reloading, but I always go off of published reloading data to avoid issues. But, I just ran across an interesting discrepancy that I'm hoping someone could help me understand. I'm prepping to load up my Mosin-Nagant ammunition with Sierra 150gr bullets. I looked up reloading data in my Lyman's 49th edition book, and compared it with data from Hodgdon and Vihtavuori. The data from VV only shows for "7.62x53R (7.62mm Russian)". In Lyman's 49th, the load data for VV N140, 150gr JSP shows as: Starting: 43.5gr Max: 48.5gr On the VV site, they state for the 7.62x53R (7.62 Russian), Lapua Mega soft-point bullet: Starting: 44.1gr Max: 49.2gr VV site for 150gr Lapua FMJBT: Starting: 47.7gr Max: 51.7gr The two jacketed soft-point bullets are similar, though VV does use a slightly higher load. But the FMJBT is quite a bit higher with higher velocities to match. I assume this is due to the stronger jacket? Does this still fall inside of the general ranges for other books' load data for VV N140 in 7.62x54R? And is load data for 7.62x53R even usable or reliable for my needs? Both rounds, the 53R and 54R, seem quite similar with only very small deviations between the two. As long as I start near the bottom and work up from there, is there any reason I should avoid looking at 7.62x53R load data for my Soviet Mosin-Nagant M91/30?