Bob,
My present lot of H4831SC is somewhat slower than my remaining batch of the original mil-surp powder.
The only .270 I own anymore is one of the recent O'Connor "Tribute" Model 70 Featherweights. As an experiment, I tried some of the original H4831, side-by-side with the new stuff, with 130-grain Hornady Interlocks, using the same 61.0 grain charge. The old H4831 got 3118 fps, while H4831SC got 3029. This was during the same range session, over the same chronograph, with the two strings shot one right after the other. The rifle will easily handle 58.5 grains of H4831SC with the 150 Partition, and velocity isn't quite 2900 from the 22" barrel.
I suspect the answer depends on the manufacturing lot of each powder.
