I have an old Speer manual that lists loads that are way above the loads in the current manuals, and I have never run into problems by working up a load to near maximum from that old Speer manual. One I can think of off the top of my head is a 180 grain BTSP in a 300 WM with IMR4350. The starting load in the Old Speer manual is 2 grains higher than the top load in several other newer manuals. My load was 4 grains higher than the max load listed in the newer manuals, and still very safe, and the manual I was using listed a load 2 grains higer than I used. I was getting 3140 ft/sec with a 180, and 5/8" groups, so I settled on that for moose. It works! I've never yet squeezed one off hunting where something hasn't died on its way to the ground. Brass life has been good.
A lot of my 30-06 loads have been near the top end over the years, and I have brass that I have used 8-10 times with no problems. Now, I am not getting 2900 ft/sec out of a 180 gr, but I was getting 2800 plus, and I am easily getting 2900 out of 168 TSX's.
Just before I bought my 300 WM, I seriously considered a WSM. I opted for the longer version because I thought it held more potential, and I still do. If I couldn't get the 300WM, I would likely have just stayed with the 30-06, and after 8 years with the WM, I returned to a 30-06 and am loving it. Still got the WM, and absolutely no flies on it, but that '06 calls my name in the night.
