A guy named Bob
Well-Known Member
Bought a pound this morning from powder valley. I have a new 6.5 PRC that I want to test with this powder. What are your thoughts as to temperature sensitivity with this powder? Thanks for any help
Norma MRP temp sensitive?
- Thread starter A guy named Bob
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cdherman
Well-Known Member
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.
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.
A guy named Bob
Well-Known Member
Thanks
Mike Matteson
Well-Known Member
I use MRP in my 25-06 with 120 gr ballistic tip Nosler for years in hot and cold weather, and never had a problem with it. In the fall and winter I am planning on running some test with it. If I get my move done quicker I will start this summer, when it's hotter. A long time ago I used the load from Nosler reload manual in hot weather in S. Cal, and used it during the fall in Cal and winter in Nev, and Utah, Montana. but I wasn't really looking at that possible problem. I talking about in the late 70, into the 90's. I move up to a 308 Norma Mag in 2000. I got an upcoming with IMR powders then. I gave away the IMR powders and never used them again. So there some info, but not really enough to be sure.
ChrisTeam2
Active Member
Hi Mike, wondering if you ever ran those tests with MRP. I am sitting on a 8 LBS jug of MRP and trying to figure out what to do with as I have all the powders that I need at the moment. If I don't end up selling this MRP powder I will at a minimum test it in my 280 with 166 gr. A-tips and with my 300 WM maybe with some 180s and/or 208 ELD-Ms.. Any temp. data you can share would be helpful. Thank you sir - Chris
I stopped worrying about temperature sensitivity for my type of shooting/hunting.
Hand Skills
Well-Known Member
This thread appears to originate from 2021, so it's likely the OP is well on his way.
But for posterity, I will add that RL23 is very close to RL22 in burn rate and bulk density, but has the advantage of being relatively insensitive to temperature.
But for posterity, I will add that RL23 is very close to RL22 in burn rate and bulk density, but has the advantage of being relatively insensitive to temperature.
Mike Matteson
Well-Known Member
Here a chart on powder and how they are rated for temps. I know I had a chart on MRP powder's, but it took me so time to find it.
I do use MRPpowder in a few rifles. I don't have one of my manual with me. If I remember correctly it was in a 25/06 with 120gr Nosler SPBT. They don't make them any longer.Other than that I don't have much on Norma powders for Temp.
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Mike Matteson
Well-Known Member
No I haven't done much. I like the powder in my 25/06's. It group well in 4 different rifles.
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ChrisTeam2
Active Member
Copy that, Mike. I really appreciate you spending the time to look into it. Thank you sir - Chris
Mike Matteson
Well-Known Member
Not a problem, and It straighten up my files some. I have a bad habbit of downloading items, and think I have where I can go right to. After that good luck. The good part is, it's make me straighten those files up, until the next time
The MRP I knew I had something on it. I have used the MRP in my 25/06 and made several 500yd shot with it. It group well for me in all the 25/06 rifles I shot. The powder is expensive too. It can be very hard to come by at the same time.
Mike Matteson
Well-Known Member
Mike Matteson
Well-Known Member
I am glad you stop worrying temp powders. Someday you'll blow a primer out of your case because to temp sensitivity powder, and wish you had paid closer attention to it. IMR 4831 changes over 1 fps per degr of change. Other words that in -20 to 110 dr, that's 130fps change. Even if you use the mean of the temp it still 65fps. 50fps changes your POI by 14" @ a 1000yds.
Bryan Litz is right on on what he's stating.
I don't generally is double base powders if I can help it anymore. Because I did blow a primer out of a case because of temp change.
I don't care what type of powder you use, but you need to well aware of possible problems with different types of powders.
Bryan Litz is right on on what he's stating.
I don't generally is double base powders if I can help it anymore. Because I did blow a primer out of a case because of temp change.
I don't care what type of powder you use, but you need to well aware of possible problems with different types of powders.
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.
(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.
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