I got two pounds of RL-17 about a month ago, and now that I've had the chance to work up some loads and test them repeatedly, I thought I might post my findings for other forum members.
To begin with, all my testing was done with 140 grain TSX bullets, out of a Kimber Montana with a 22" barrel. I tried many different 140 grain bullets, but for some reason my Kimber shoots the TSX's far better than any of the other bullets I tried.
Before I go any further, I'll offer the usual warning that I worked up to all loads slowly and carefully. Often, as I knew I was reaching a point where I was pushing, I would fire ten or more rounds at a certain level before sneaking any higher. Since I'm not using any pressure-testing equipment, I have no illusions that I stayed under SAAMI specs. I can add that my brass is on it's sixth reloading, and primers still fit tight. I neck size only, and I did anneal the necks and bump the shoulders after the fourth firing. I will also add that I have not (yet!) had the chance to test ANY of these loads at temperatures over 40 F.
I tried many different powders, and had found that RL-15 and Varget performed best, meaning that they gave me a good combination of accuracy, velocity, and low ES and SD. I pushed both until primers flattened and I got the occasional sticky extraction, then I backed off half a grain. After much back and forth and many rounds fired, 45.5 grains of RL-15 ended up being the best of the two. Temperature stability of RL-15 seemed pretty good too, although, this being winter in Alaska, I never got to test it at above 40 degrees F. However, from about -5 deg to 40 deg F, I found next to no difference in velocity or pressure.
At this point I was getting an average muzzle velocity of almost exactly 3000fps and an SD of 16fps (over ten shots), and MOA accuracy out to 200 yds.
I was able to match this velocity, with less pressure, using 50 grains of RL-17. I reached a compressed load of RL-17 before seeing any pressure signs, so case capacity seems to be the limiting factor. I've now fired over 30 rounds at this level, and none of them showed any sticky extraction. Accuracy and SD are close to the same, although RL-15 may have done slightly (barely noticeable) better in both categories.
I do think that RL-17 is good in the 7mm-08, although it seems that case capacity can be the limiting factor. For 140 grain bullets it does very well, but I think RL-17 would be IDEAL with a slightly heavier (145 gr?) bullet in the 7-08. IMO with lighter (120 gr) bullets, RL-15 seems about ideal. As advertised, RL-17 seems more ideal for WSMs. For now though, I'm going to go with it as my go-to powder for the 7-08.