The 70 grain Speer was designed to stabilize in slower twists even w/ not so fast velocities because of the shape. It is similar to the 6mm/244 problem. A 100 grain spitzer will not stabilize in the slower 1 in 12 twist of the .244, but the round nose Hornady 100 grain will. The problem w/ the 70 grain Speer is that it has to be seated deeply in order to chamber. This can cause higher pressures due to reducing case capacity. The only way to know for sure is to try the load in the rifle in question. Sometimes they stabilize and sometimes they don't. This just proves that each rifle is an entity unto itself and some will deviate from the norm.