Temperature stable powders

coachA

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Mar 23, 2013
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Guin, Al
I have been reloading my 7mms rem mag with 162 ELD-X pushed by 60.5 grains of RL 22 and getting 1/2" groups consistently. I am not sure how temperature sensitive RL 22 is. I just wondering if there is a better powder available out there? I know there was a thread on here talking about RL 23 and 26; but I would like to know what you guys are having best results with?
 
best results for me in my 7rm is IMR7828 with 140 to 162gr anything higher then it is rl22 or 25. What it really likes is cci mag primer, 150 sp & 67.0 grn IMR7828. This is a very close to max load so I would work up to it
 
I have had severe pressure spikes with Alliant and the older IMR powders only hot days.
I now only shoot Hodgdon line of powders with no problems.
Steve Bair
 
I know it's not a 7mm mag but my 270 weatherby mag shoots very consistent with retumbo and the heavier bullets. Temp swings don't seem to change it much at all.
 
I did a test just last week, let the rounds freeze outside in 20* weather and laid bullets on the heater vent of my truck for 30 mins.

Measured over a magnetospeed I had a 125 FPS difference between the hot and cold rounds.

This was with reloader 22 - 200 gr. 200 eldx

Hot rounds-2925 FPS
Cold-2799-FPS
 
I did a test just last week, let the rounds freeze outside in 20* weather and laid bullets on the heater vent of my truck for 30 mins.

Measured over a magnetospeed I had a 125 FPS difference between the hot and cold rounds.

This was with reloader 22 - 200 gr. 200 eldx

Hot rounds-2925 FPS
Cold-2799-FPS

Good example
 
It never fails that I do hunting load workups in July and August (90 degrees) and then am left wondering on days like today (7 degrees this morning) what the heck my drops will be. Makes you feel silly for working so hard to find loads that group well and then you Have no clue what is happening when the temperature changes 70 degrees. Glad i saw this post today. Will add cold and hot workups to my "to do" list for 2018. My local hunting temps vary between 5 and 75 degrees. I used RL 22 in my 280 Ai for a few years.
 
I live out west where it gets 100F+ and have found most powder really shoot up in velocity/pressure around 85F. These include RL17, 22, 26, 33, as well as IMR7828.
I have found H4350, H1000, & Retumbo to be stable over 100F when my load work ups were in the 60'sF range. I'm not sure what they do in the extreme cold but I don't have that here. BTW New Years day was 77F here in North LA County, CA
 
Click on image to enlarge

33XPgx3.jpg
 
I have to add Varget to that list as well.
The single base powders have much less(about 1/3 less) variance per degree of temperature change than double base powders.
Just remember, if your temperatures aren't within the extreme fringe of HOT you are probably fine(not pushing max). I have almost 6 months where it can hit 90-100F so these powders have to be good at HOT temps or they can be dangerous.
 
RL16 for creedmoor sized cases is showing to be very temp stable. A shooter on Accurate shooter has a very small temp drop from 70s to 30s, I think they were the temps at least. I have some but no velocity data from the summer in my creedmoor. I am currently getting a load fine tuned for my 7saum with RL23. I'm just looking for predictable velocity and accuracy not max velocity with accuracy so as far as I'm concerned RL26 isn't for me despite it being relatively temp stable for some.

Another powder for magnum cases about to come out is IMR8133 which is currently listed in Hodgdons online data despite it not being stocked anywhere to my knowledge. It's showing top speeds in some cartridges like 280AI and I think 7mm Rem Mag. I'm looking forward to trying it in my SAUM.
 
When you get to the extreme cold even the Hogdon extreme line drops in velocity. It was -35C here recently and i had to reset my dope minus 125fps for my 308 and 6.5. That's approximate...I've found them to be quite stable to -10 to -15celsius. That's with varget and h4350
 
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