Re: 300 ultra
I used H-1000 when I tested and shot the 220g SMK. I will have to get my book out and see the data. Yep, 88g of H-1000, CCI BR-2, yes I know its only a large rifle primer, but it works!! OAL was 3.750" My data book shows 3025fps with a 1.3" 3 shot group at 300 yards. I also have a couple loads from others that have shot very well in there rifles, its off accuratereloading. Try 90-91g of Retumbo. Or 88g to 92g of H-1000. All those loads were under .5". Hope this helps.