With the 250 and 300 gr SMKs I have not been able to get them to group in my .338 LM rifle with the stock barrel or the new 30 inch custom McGowen without being at least .020 and .025 - .035 works better for me. I have noticed that at 400 yards and up .1 grains of powder make a difference in groups with my new barrel. I have not worked with RE33 enough to give any advice about the powder but I am working with it. I started out (3 years ago) working with and perfecting loads with IMR 7828 Fed 215 or Tul-Ammo LRM and Lapua brass for 3016 fps with the 250s and US 869 for 2957 fps with the 300s. Both loads are sub MOA at 100 yards. The 250s and 7828 are my go to load as it produces 2.16 in. 5 shot groups at 600 yards. Just my 2c. Hope this helps in some way.