It was quite foggy this morning. I could not see the target at 100 yards so I moved closer to 65 yards. Is it reasonable to expect that if group size was 0.3� at 65 yards then it would be 0.45� at 100 yards? I was shooting the Sierra 220 Matchking in a long throated 300 Win Mag. This bullet is touching lands at an overall cartridge length of 3.565�. I started load development with the bullet just touching lands. I am using Federal cases and Federal 215 Match primers. The rifle is a hunting rifle (8.3# without scope and sporter style stock) so I am not expecting 0.25� groups at 100 yards. I decided to test RL25 initially. Perhaps I will also try H1000. Groups were 3 shots and again they were at 65 yards due to fog. I started with 71 grains and got a 0.77� group. 72 grains gave 0.54� and 73 grains gave 0.31�. I think I can go up more in powder. Also I have not messed yet with seating depth. Are any of you using this combo of powder, bullet and case? If so where have you reached max charge and where do the bullets generally like to be seated in relation to the lands? What kind of velocity should I be able to get from a 26� barrel? Would H1000 be better? Thanks, Rufous.

rufous - I shoot a Win Mod 70 Laredo in 300 Win with the 200 MKHP. I use the same seating depth of 3.565" which puts the 200 MKHP into the lands by .005" in my rifle. My load for LR use is prepped Win cases, Fed 215 Match primers and 70 grains of Reloader 22 for 2785 fps. I have increased the powder charge up to 73 grains for 2883 fps avg without loosing accuracy. I have not used H1000 or Rel 25 because Rel 22 works so well.
I have shot out to 1000 yds with it and found my group size, moa, was better between 300 and 500 yards than at 100 yards. I have shot at 30 and 50 yards and found the group size to be approximately the same as I get at 100 yards. I attribute this to the long bullet stabilizing at around 200 yards.
It sounds like you are close to or at the "sweet spot" for your rifle with the 73 grain load. I like using a little less powder instead of hotter loads as has been discussed before.
I have worked up loads using different seating depths with good results. If you seat into the lands then start powder charges lower and work up again to avoid the higher pressures. With this rifle I get better SD's, ES's and LR accuracy with the bullet slightly engaged into the lands. FYI - my 338 RUM does not like bullets into the lands and accuracy falls off. You can only try.

I went out again this afternoon. It was not nearly as foggy. I set the target up at 200 yards at tried the 73 grains of RL25 load again that gave me a 0.31" group at 65 yards. It was 1.78". Then I tried 74.0 grains and got 1.25". 74.5 gave 0.5" and 75.0 gave 0.74". Looks like 74.5 grains is my load. I hope to try it tomorrow at longer ranges. I have not yet started fiddling with seating depth. I just have it touching the lands, but if I can duplicate that 1/2" group at 200 yards I probably will just go with that. I do not know what the velocity is but am guessing it is in the 2750 to 2800 fps range. Rufous.