In my .204 Ruger IMR 4166 did a fine job with Berger's 35gr bullet, CFE223 did better with some others, and at least has the decoppering element,but H4895 and RL15 also had great combinations. The rest of my bottleneck centerfire rifles are pretty much interchangeable, 6mm Rem, 250Imp, .270 Win and this .300 are probably equals for deer the way I hunt them. The 6mm's a 788 that now wears a #5 contour Shilen bbl in place of the original so weight takes it out of the deer picture, IMR 4551 made up a good version of the load I used in the original barrel with an 80gr Blitz, hopefully it or 4166 will do likewise for an 87gr V-max. For such rounds a powder to keep velocities relatively constant under varying weather will be appreciated.
The other deer calibers can likely continue using what has worked for them in their use, the silhouette shoots have been summer events but I'll pay more attention to velocities in say 70deg vs. 90deg+ conditions. Should be easy to work up something for each in their given bullet weights with these two Enduron selections, if current favorite with other powders show sensitive to cold. I don't think I'll ever shoot anything to equal the rate of fire in the silhouette matches with these bigger calibers,
One thing that's been consistent from hot to mild wx, admittedly not checked in the cold, is a favorite load for the Speer TNT in the .250AI. That one uses WW760 and always shoots fine groups with consistent velocity. I'd be happy to construct a cold weather variation if needed, won't give up the 760 though.
A friend who worked a rod and gun club in Spain in the 80s told me they got their shotshells through a local distributor and they appeared to change the recipe as the weather changed. Shells purchased in the winter gave noticeably increased recoil if kept through to hot weather and fired then, and the supplier told him they were loaded with a powder called Santa Barbara, available for reloading as well. This was a flake powder that looked like Unique, apparently considered sensitive enough to temperatures that the producer altered the charges to compensate. Might be true.
