Possibly Indeed. - The loads I’ve ran RL-33 in the 338 Lapua Imp. and a 28 Nosler (both with longer barrels) the fill rate is +95% and heavier bullets are used.I can tell you the couple loads I developed with RL33 were showing near 2fps per degree change. Not anywhere near stable in my book. N570 on the other hand has been well under 1fps/degree and usually closer to .6-.7 in the few loads I have shot it in. Based on what I have seen/read it seems as if RL33 is more dependent on the fill rate of the cartridge and bullet weight used where I have not seen or experienced that with other powders. I personally would stay with N570.
Based on the reports like this and those of others I would agree. RL26 is another example some claim poor temp stability but in the 5 or 6 loads I have tested it has been very stable.RL33 is very stable in my 338 lap imp. I dont know about hot temps but in the mild to cool temps it beat h1000 for day to day velocity stability. I believe the reports of it being sensitive for some guys, but I think you need to test it in your chambering and conditions to see how it does.