I am near out of IMR7828 in my 300 win. mag. and it has worked ok but not fantastic. I am considering going back to H1000 or even trying Retumbo. I have a 26" barrel and have been shooting 240gr. MK's and also the 220gr. MK's. Both shoot well in the 1-9 twist. Im sure the H1000 will work fine but I was wondering if I have enough barrel to warrent the slower Retumbo. Im going to stick with the extreme powders from now on. To much temp changes in this country.