Bought a set of Dies for the .270 Win yesterday along with some 160 and 150 partitions. Opened the Nosler guide and they recommend the usual IMR 4350, IMR 4831, RL22 and RL 19 for the 160's bullet. But as for the 150 Partition the IMR 4350 and IMR 4831 is not even listed and is replaced by H4350 and H4831. My question is, what is the difference between the two? And If I substitute IMR for the Hogden will it be dangerous? What is so different that for the 160's IMR is good but when you step down to the 150's hogden is good.............had me puzzled on this one