Norma MRP temp sensitive?

[Lefty7mmstw]

I stopped worrying about temperature sensitivity for my type of shooting/hunting.

Me too. I just buy a big enough hammer to start with, then give it a bit of head room. Then I test in hot and cold temps. before I hunt the load. I live where I live you can often test hot/ cold in the same week.
I'm not buying that mrp is better than rl22. It used to be the data was about interchangeable and both powders came from the same factory.. I'm also not buying that temp stable powders are always temp stable and non temp stable powders can't often beat them overall. I've done a lot of shooting over my Oehler's over the years that tells me otherwise.

 

[Mike Matteson]

I am well aware of the attributes of the powders I use for my intended purpose, and I always test them for my hunting thresholds and adjust accordingly. I also do not develop a load that can perform in the -20 to 110F range. I usually finalize my load development for my hunt in October/November at the end of September.

View attachment 567948
(https://weatherspark.com/compare/y/...-in-Billings-Missoula-Bozeman-and-Great-Falls)

So, yes, I pay close attention to all my load developments, and thus far, there have been no blown primers.

If you are sitting in the cities. I am out of Missoula. Seen it colder that their coldest, and sure gets a lot hotter than there temp showing. Now go into the mountain and see where you are. You got to look at the very Lows and Highs. Missoula get a lot hotter than 53dr. You can cherry pick you temps. I hunt in area that can and have been -20 to areas that are 110+. I have also hunted in 6 different states at different times of the year. Elevation from about 700' to 9500'. So you don't get to cherry pick your temps. You hunt in what it is. Or maybe you can, but I never had that going for me, because I hunt in any weather. I don't cherry pick my weather either. So your chart really doesn't work.

 

[FEENIX]

If you are sitting in the cities. I am out of Missoula. Seen it colder that their coldest, and sure gets a lot hotter than there temp showing. Now go into the mountain and see where you are. You got to look at the very Lows and Highs. Missoula get a lot hotter than 53dr. You can cherry pick you temps. I hunt in area that can and have been -20 to areas that are 110+. I have also hunted in 6 different states at different times of the year. Elevation from about 700' to 9500'. So you don't get to cherry pick your temps. You hunt in what it is. Or maybe you can, but I never had that going for me, because I hunt in any weather. I don't cherry pick my weather either. So your chart really doesn't work.

Those are average temperatures; yes, I am fully aware of the actual temperatures, but they are unavailable to share, especially in my hunting areas. The chart is meant to show the temperature for a fall load. As previously noted, I do NOT load to perform -20 to 110F. Is that too hard to understand? And yes, I can cherry-pick the temperature I am going to hunt, and yes, the temp chart works and has been for many years without any issues. I have different loads for different occasions. The fall loads are my MT general rifle season load.

I, too, have hunted in different states. When I was stationed in AZ and NM, my loads were different from mine in MT. But I still load them for the fall season. I do not know why you find that difficult to understand. If your load works for your intended purpose, that's great, then move on. Nowhere did I try to convince anyone to do the same as I do. Yes, I still have and use the extreme line of powders. I used to be an extreme powder-only user. So, yes, I take the time to learn about the powders I use for the environment I intend to use. It is more realistic for me to load a fall season load where the temperature spread is more manageable instead of expecting a powder to perform from -20 to 110F. The bottom line is to worry about your load for your intended purposes, and I will do the same.

 

[Quintus]

If you are sitting in the cities. I am out of Missoula. Seen it colder that their coldest, and sure gets a lot hotter than there temp showing. Now go into the mountain and see where you are. You got to look at the very Lows and Highs. Missoula get a lot hotter than 53dr. You can cherry pick you temps. I hunt in area that can and have been -20 to areas that are 110+. I have also hunted in 6 different states at different times of the year. Elevation from about 700' to 9500'. So you don't get to cherry pick your temps. You hunt in what it is. Or maybe you can, but I never had that going for me, because I hunt in any weather. I don't cherry pick my weather either. So your chart really doesn't work.

I have a similar guide to Feenix' chart and it works very well. Long before there were 'temp stable' (Hodgdon was not always labeled so) I discovered that loads worked up in cool weather would pressure badly shooting P-Dogs in the summer. I ended up with summer p-dog loads and regular big game loads and below zero big game and coyote loads. With just a little research and then experience I ended up with loads I know will work well in say 3rd rifle in CO. Yes, it could be -10 or it could be 60 and may well be both over that week. I have loads with RL26 and IMR4350 that work very well in that range. I would not take either of these loads hunting desert sheep in Mexico or hogs in south TX.

 

[baldhunter]

I'd like to know how many times Hodgdon performed that 0-125 degree test on their publication.How many times did they repeat it?How many different lots of powder where tested?Same seating depths on the bullets?Powder charges may have not been suitable for the cartridge and bullet.Just way too many variables to believe everything you see published.Your better off doing your own testing with what your shooting.

 

[65WSM]

I have what's left of an 8 lb jug of MRP that I bought at some vague point in the last 10 years. I tried it in a number of guns and never was quite happy enough. I never had a complete temp sensitivity disaster, but I don't load hot. But I did not get session to session accuracy retention that I would like.

IIRC, I read a LOT about temp sensitivity, as I hunt in Kansas, where it can be zero in deer season, and it might have been 95 when I developed my loads. MRP was reputed to be better than some of the Alliant powders (the old one's like RL-22) in terms of temp sens, but not as stable as the Hogdon temp stable series (H4350, H4831, H1000 etc)

There also were rumors that MRP was the SAME as RL-22. This is not likely true, but they are very similar powders in terms of burn rate and density.

 

[65WSM]

I have what's left of an 8 lb jug of MRP that I bought at some vague point in the last 10 years. I tried it in a number of guns and never was quite happy enough. I never had a complete temp sensitivity disaster, but I don't load hot. But I did not get session to session accuracy retention that I would like.

IIRC, I read a LOT about temp sensitivity, as I hunt in Kansas, where it can be zero in deer season, and it might have been 95 when I developed my loads. MRP was reputed to be better than some of the Alliant powders (the old one's like RL-22) in terms of temp sens, but not as stable as the Hogdon temp stable series (H4350, H4831, H1000 etc)

There also were rumors that MRP was the SAME as RL-22. This is not likely true, but they are very similar powders in terms of burn rate and density.

Different importers from Bufors. I remember when Norma 205 first became available for a short period of time in the US (it was replaced on the shelf by "MRP"). Jack OConnor devoted a column in Outdoor Life to handloading the .270 Win with several different bullets (150 gr for his Wifes rifle for Africa) with Norma 205. Later Reloader 22 was imported by different characters in America, and Jack had another handloading episode.

 

[Philward]

I am well aware of the attributes of the powders I use for my intended purpose, and I always test them for my hunting thresholds and adjust accordingly. I also do not develop a load that can perform in the -20 to 110F range. I usually finalize my load development for my hunt in October/November at the end of September.

View attachment 567948
(https://weatherspark.com/compare/y/...-in-Billings-Missoula-Bozeman-and-Great-Falls)

So, yes, I pay close attention to all my load developments, and thus far, there have been no blown primers.

Interesting chart, I didn't think GF would be warmer across the board than the other major cities in Montana.

 

[Mike Matteson]

I have a similar guide to Feenix' chart and it works very well. Long before there were 'temp stable' (Hodgdon was not always labeled so) I discovered that loads worked up in cool weather would pressure badly shooting P-Dogs in the summer. I ended up with summer p-dog loads and regular big game loads and below zero big game and coyote loads. With just a little research and then experience I ended up with loads I know will work well in say 3rd rifle in CO. Yes, it could be -10 or it could be 60 and may well be both over that week. I have loads with RL26 and IMR4350 that work very well in that range. I would not take either of these loads hunting desert sheep in Mexico or hogs in south TX.

I became aware of temp stable powder in the 1998 or so. I had a primer come out of the case with IMR 4381 or IMR 4350. Temp change was about 50 to 70 dgr. (Not sure just how much) I am not saying that I wasn't loading hot, because I was. I became aware of Hodgdon powers at that time. Two other factor is: Mostly I use H4350 because it one that doesn't change much in a wide swing of temps. It's doesn't change much in temp from on end to another -20 to 110. 50fps changes your POI by 14" @ 1000 yds. I do believe that most shooter don't realize the problem in changes in velocity or SD. I see from time to time people here showing case with ejector makes on there case. When were those load develop and what temp.
The other is I develop a load that I can shot in cold bore shots in all type of weather, and I hold my range to 500yds. i use rifle that the velocities petty much match each others. That way, I don't have to think about which rifle or the POI is at.
At the time I used IMR powders I got better velocity from them, and accuratic was very good also. IMR4831 changes about 1fps and IMR changes about 2/3fps. So if you are not aware of those possible problems, you can be in a huge hurt locker.
At that time I gave away about 16lbs of IMR powders and haven't used them going forward.
Like I say use what you want. Just want people to be aware of the possible problems.

 

[FEENIX]

Interesting chart, I didn't think GF would be warmer across the board than the other major cities in Montana.

They are average temps. Yes, it actually gets colder. I remember a few occasions with -50s with windchill factor.

 

[Mike Matteson]

Different importers from Bufors. I remember when Norma 205 first became available for a short period of time in the US (it was replaced on the shelf by "MRP"). Jack OConnor devoted a column in Outdoor Life to handloading the .270 Win with several different bullets (150 gr for his Wifes rifle for Africa) with Norma 205. Later Reloader 22 was imported by different characters in America, and Jack had another handloading episode.

As a kid I read Jack OConner all the time. I finally got to Africa twices.