powder data for temperature swings

ohiohunter

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Anyone have data on powder for temperature swings? Fps loss or gain in different temps?


Too vague of a question, some guys know how temp effects their particular loads but each load will vary. Personally I would worry more about pressure than fps. The only way to know for sure is to chrony your rifle.

There are some guys who have illustrated the effects of temp on their loads but they are few and far between. Thats why I only shoot hodgdons extreme powders... "whats the temperature?".. who cares.. hunt.
 

AZShooter

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Here is a powder that has a pretty bold statement about its lack of temperature sensitivity:


IMR 8208 XBR "totally insensitive to changes in temperature."




IMR 8208 XBR The latest in the versatile IMR line of fine propellants, this accurate metering, super short grained extruded rifle powder was designed expressly for match, varmint, and AR sniper cartridges. Ideally suited for cartridges like the 223 Remington/5.56mm, 308 Winchester/7.62mm NATO and the 6mm PPC, shooters will find IMR 8208 XBR totally insensitive to changes in temperature, while yielding max velocities and “tack driving” accuracy. Clearly, the competitor’s “choice” and the Varmint Hunter’s “dream powder”.

I use it in my 308 and 6 BR and don't worry about the temperature.
 

Bbear

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I have noticed my loads with some of the Reloader powders (19, 22 & 25) that are accurate at hunting temps (20F-60F) are 100 fps or more faster when I shoot the same loads in the summer time heat (95F-110F). Anxious to see what the new RL 23 and 26 will do.
 

elkaholic

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I have noticed my loads with some of the Reloader powders (19, 22 & 25) that are accurate at hunting temps (20F-60F) are 100 fps or more faster when I shoot the same loads in the summer time heat (95F-110F). Anxious to see what the new RL 23 and 26 will do.

Can not tell you about temp sensitivity but ES is absolutely AMAZING and velocity is as good as it gets in my 6.5 Sherman and 6.5 Sherman Shortmag with RL26. I had single digit ES consistently, and some three and four shot strings were only 2-3' and one string only 1'. I have never seen es this low. No, it was not the chronograph! I was using a mag speed and tried another powder at the same time which gave me spreads of 40'.......Rich
 

Lefty7mmstw

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Can not tell you about temp sensitivity but ES is absolutely AMAZING and velocity is as good as it gets in my 6.5 Sherman and 6.5 Sherman Shortmag with RL26. I had single digit ES consistently, and some three and four shot strings were only 2-3' and one string only 1'. I have never seen es this low. No, it was not the chronograph! I was using a mag speed and tried another powder at the same time which gave me spreads of 40'.......Rich

Sometimes you just get those super low x's and wonder why the heck the other loads didn't perform as well. We set up my Pop's Tikka 300win a few weeks ago and one load with the 180 hdy and 7828sc has a 2fps X variation!!!

As to rl powders, they have never let me down, as long as they have a powder that is a proper burn rate for what I'm doing. I currently use all reloader powders other than rl10x and rl23. They have a bit of vel. change with temp swings but it is predictable. I've also seen other variables come into play and make a "temp stable" powder like h4985 swing a bunch. A powder may be nearly temp. stable in one combo and vary 80+ fps from hot to cold in another.
 

Darkker

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There is no answer to the original question other than, "it depends".
Temp insensitivity is only that when under conditions designed for, or very similar. So for example, Varget was designed around the 308 with 145-155gr bullets. Very insensitive there.
However you move Varget to the 223 & 55gr bullets.... While the resulting groups can be very good, the temp resistance is a miserable failure.
Do some searching for Dr. Denton Bramwell. He contributed to VHA, and the RSI website; has some very good scientific testing on this very subject.
 

elkaholic

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I do agree that this varies by cartridge and circumstance from powder to powder. That said, in my 6.5's and in some other Sherman users, RL26 has been amazing and consistent with low ES. I haven't seen that in RL 23 yet, but I haven't used it as much either. I have found (so far) that the RL powders made in Switzerland (RL 33, Rl 26, RL 17, are more consistent than the Swedish made powders like 22, 23, and 25......Rich
 

Darkker

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RL-17 is built by German defense contractor, Rhinemetal.
The others listed are by Group SNPE, a French state-owned defense conglomerate that controls Eurenco.
 
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