They are both temperature sensitive. I believe 748 is more sensitive than 335 and both powders produce greater pressure as ambient temp increases. Of the two, I prefer H335 for bullet weights between 50 and 60 grains. It has yielded more consistent results in my experience. YMMV . . .Looking for experience between these powders in 223 rem with 55gr bullets. Looking for results in high temps and cold temps. Are they really that temperature sensitive? Should i use magnum primers? Thanks.