I will have to let someone else give you a definitive answer on that. I have never had any trouble with temps with 7828, and I use it in a couple 300's and 338's. IMR 4350 and 4320 have worked well for me at all temps in smaller calibers. I had a conversation with John Lazzeroni and he recommends 7828 for use in his Warbird caliber. I have read on a couple of sites and one magazine article to stay completely away from (I think) IMR 4895. I have some of that but have never used it.
Check the 7828 can and see if it says "extreme" on it. That would indicate it is an all-condition powder, likes H-1000 does. Perhaps someone else will jump in here and we will both learn something. I agree that it is nice to have options, and I have tried a lot of powders, but when you hit one that gives you the performance you want, you get reluctant to experiment to avoid unnecessary wear on your rifle. H-1000 has always been my "go-to" powder in a lot of loads. Have your tried any of the reloder powders? They give excellent performance over a wide variety of calibers if you just stay away from extremely hot environmental conditions.
As long as I mentioned barrel wear, I will throw in a little info I got from barrel and custom rifle builders. I had my .257 STW built immediately after Layne Simpson introduced it in one of the magazines he writes for. It has all the makings of a true barrel burner...a 8mm magnum case necked down to .25 caliber that burns a ton of powder to push a 100 grain bullet nearly 4000 fps. I started at 20% under Simpson's recommendations (he published a whole page of loads with the article which has saved me a lot of money experimenting), but they were still way to hot for my rifle, which obviously is underbored, but lethally accurate to very long distances. It is not a short range rifle unless you load it way down, or it just blows deer up. I discussed barrel life with the builder, who I prefer to not name since I do not have his permission to use it publicly. He would probably appreciate the mention, but you never know. Some guys are touchy about that and I might want to use him again so I do not want to offend him in case he stumbles onto this post. Anyway, he stressed two things to make a barrel burner last a lot longer....one is temperature, and the other is compulsive barrel cleaning. He said to never let a barrel get above 165 degrees. I bought a little laser temp tester at Sears, and check the barrel temps on all my rifles regularly. I have no solid evidence that it has extended the barrel life of this rifle, but it probably has about 1000 rds through it with no loss of accuracy. My 22-243 Middlestead has had a couple thousand through it, and it is starting to lose a little. But we are talking about a rifle that pushes a 50 gr. NBT at 4500 fps. I think that I just read that the 22-243 holds the record somewhere in the high 5000's.
When Lazzeroni sent me my rifle, he told me that when I clean it to swab a good copper solvent into the barrel, let it sit for about fifteen minutes, then run a brass brush through it a minimum of 120 strokes, then start running swabs through it until they come out spotless. I was aghast. Run a metal brush through a barrel 120 strokes every time you clean it? Granted brass is much softer than the material in John's barrels, but still, it's metal on metal. But, I have a lot of respect for John's carefully guarded opinions, so I decided to try the method on my 300 Win mag Sendero which has been shot heavily for 16 years now, and half-inch groups had grown to inch and a half groups over the years. I clean my guns scrupulously, and the barrel on the 300 was bright and shiny and the lands were sharp, but I decided to try Jon's recommendation. At about stroke number 50, black gunk started to come out of the barrel in chunks. Where the hell it had been hiding, I have no idea. By stroke 100, things were looking much better. I went all the way to 120, then started with swabs, and after about five swab, I swear to God, they were coming out as clean as they were going in, and I had a pile of dirt on the floor under the end of the barrel. Obviously, this really intrigued me, so I was off to the range to see if all that work translated into improved performance to my old warrior. I fired one fouling shot, than shot one five shot group at 100 yards. It measured.4 inches. Two more groups were comparable. I was dumbfounded. My all-time favorite rifle had just been resurrected from the dead.
If I have learned nothing else in 42 years of shooting, it is to always listen to what the other guy has to say, analyze the info, maybe try it out, but never ignore it. I have not tried this cleaning process on my 22-243, but fully intend to as soon as my new knee works right and I am back in business. (Everyone, please forgive my verbosity. I am an ex English lit and writing teacher, and once I get started, I just can't keep anything short. Further novels are coming, I am reasonable certain.) Thanks for your indulgence.
Old Teacher, your writing style flows well and is very easy to read. Keep up the good work, you get an A..LOL
I will have to try that cleaning technique on a few of my old guns and see how much I get out of the barrels.
I have quite a bit of experience with big 338s (Lazz Titan, 338-378 Wby etc)))) ,,,, and for a 338 RUM, I could not think of a more perfect powder choice for it, than reloader 19, with bullets 225gr and lighter ,,,,,,
IMR-7828 with bullets 250gr and heavier ,,,,,, federal 215 primer only ,,,,,,
I wholly agree with one exception. I love the Reloder powders, and given a good choice from the manual, will go with them whenever feasible. I have never had very good luck with the federal primers, even though everyone seems to advise to use them. The proof is in the calipers, and I have almost always gotten better groups with Winchester magnum primers. I have also had five misfires with Federals, one of which cost me a decent four point. I have never had a Win. primer misfire. But as I always say, if it works for you , keep doing it, just keep an open mind.
MY favorite load is 90 grns of retumbo and a 300 smk @ 2820 fps. That's out of a Krieger 30 1/2 br barrel, 1-9.35 twist. I've slowed it down and went faster but this shoots the best. 20lbs and a brake make it kick like a .243 only slower. I've shot this brass 10 times and it's hammerred, the heads even swelled to stick in the bolt.
Wow that's pretty hot!
I tested a few loads today with the 225 SST's: with 89.5 grains of IMR7828 I got 2900 fps, I bumped the load up to 90.5 grains and the chrono read 3114 fps. The bolt was not sticky but the case has a pretty good extractor mark on it, I've attached a picture to see if anyone with more experience could tell me if there are some pressure signs that I should look for.