Steve - and others. These are loads for a standard 270 winchester. I bought some h-380 for custom 26 in barrel 270. The intended load is just 100 grain SP. H-380 is listed in burn rate charts between IMR4230 and IMR4350. Max FPS is attained in my chrono work out of my bigger 29 barrel with 4350 60 or so grains at just under 3600 fps. My thinking with a shorter barrel and all winchester cases is a hotter powder is in order. The problem is many books give much less grain loads for H-380 than even 4064. I don't think that it has ever been fully tested I have a book on powders and they say that h-380 has a very wide spread between lots. The book is the third addition of Propellat profiles. Whats your take? 4320 52gr. and mag primers was the low 3400's pretty flat primers. I think that the pressure wave is to fast. I was also looking at some other powder between 4320 and 4350. h-380 is such fine ball. I did some 54 grain with CCI large rifle, but because of snow I have not tested them yet.