SenderoMan
Well-Known Member
Tagged. Just switched from RL22 to H1000 just for this reason, due to doing some research and listening to others results. Should be some interesting testing.
Thanks guys!
Thanks guys!
Truth about Temp. Sensitive Powders
- Thread starter carriecook
- Start date
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MudRunner2005
Well-Known Member
People say 19 & 22 are supposed to be very temp stable... Personally I use Alliant powders for fire-forming. Seriously. I know I'm gonna get flamed bad for that one, but it's the truth. I still have alot of cases to form for all my Ackleys, so I picked up the last 4 lbs of 22 and the last lb of 19 at my local store, a couple weeks ago. 
I have done that test years ago with IMR4350 in my 280 and last year with RL17 in a 300 wsm.Ipicked days in the 90's and put half the rounds in the freezer over night and the other ones in my truck while I was at work.The 280 surprised me becaused there was a little change in speed and the grouping stayed the same ,but the ones in the truck moved 5 inches to the left. Now the 3oo was a differant story.The ones in the freezer shot a half inch group.The ones left in the truck where all over the target,I never had two shots close together and started to show signs of pressure.The speed varied around 35 fps .I cleaned the guns after each set.I would let the barrel cool as best I could .I even put the guns in my truck with the A/C on to see if that woul change anything.The 4350 changed very little,but everything I did with the RL17 had some affect to itThis summer I want to try this with my 300 rum using RL25 and Retumbo.
gillettehunter
Well-Known Member
Be interesting to see everyones results. Tag Bruce
270Weatherby
Well-Known Member
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- Aug 17, 2009
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Tagged... I use a lot of 7828ssc in my 270WBY and my 300WBY. so far so good. very consistent.
chad
Well-Known Member
I know reloaded 19 is NOT temp stable.
MudRunner2005
Well-Known Member
Same here, I've had a great experience with 7828 SSC, so far.
Hate to waste space but tagging in since the thread subscribtion hasn't been working for me.
This is good info, it would be pretty cool if everyone with an ohelher or magneto speed created a standard temp sensitivity test, to put all the powders they could come up with through. Just to see how they hold up to manufacture's claims and have some good info.
This is good info, it would be pretty cool if everyone with an ohelher or magneto speed created a standard temp sensitivity test, to put all the powders they could come up with through. Just to see how they hold up to manufacture's claims and have some good info.
RL-17 Test Results:
Bottom line seems to be it is very temp sensitive.
Tests:
Used Marble's overnight in the freezer method. Rounds were placed in -20 deg. freezer for 20 hours. Total of three rounds in double zip lock bags. Next day placed them in the bottom of a lunch cooler and covered with 6 frozen water bottles.
Time between placing the rounds in the cooler and firing was a little over one hour.
Cold rounds were fired first from stone cold barrel that had been fouled a few days earlier.
Time between rounds was 2 minutes with a 15 minute cooldown before firing the warm rounds.
All rounds were fired within 10 seconds of removing them from the cooler.
Air temperature at the time was 64 deg.
Results:
Cold rounds:
1) 2818 FPS
2) 2799 FPS
3) 2750 FPS (odd ball one)
Average = 2789
SD = 35
ES = 68
Air temp rounds:
1) 2885
2) 2890
3) 2878
Average = 2884
SD = 6
ES = 12
Difference = 95 FPS slower for the cold rounds.
That was more than I expected. If you throw away the odd ball cold round, the difference would have been about 66 FPS.
One issue is that I do not know the temp of the rounds pulled from the cooler. Though I would expect them to be under 32 deg. I just don't know how much the temp rose from the freezer to the range while in the cooler. I will test this again, as I really like the performance of the RL-17 in MY 300 WSM and will use a infrared thermometer to get the temp of the rounds before firing.
Also, in a thread from 2011, a member stated that he tracked the temp performance of RL-17 across 1000 shots and determined that the rate of change was about 2 FPS per degree change in temperature. Using that scale, calculates the temp of the cold rounds to have been 17 deg. when fired. Pretty cold.
Below is quote from the member.
Bottom line seems to be it is very temp sensitive.
Tests:
Used Marble's overnight in the freezer method. Rounds were placed in -20 deg. freezer for 20 hours. Total of three rounds in double zip lock bags. Next day placed them in the bottom of a lunch cooler and covered with 6 frozen water bottles.
Time between placing the rounds in the cooler and firing was a little over one hour.
Cold rounds were fired first from stone cold barrel that had been fouled a few days earlier.
Time between rounds was 2 minutes with a 15 minute cooldown before firing the warm rounds.
All rounds were fired within 10 seconds of removing them from the cooler.
Air temperature at the time was 64 deg.
Results:
Cold rounds:
1) 2818 FPS
2) 2799 FPS
3) 2750 FPS (odd ball one)
Average = 2789
SD = 35
ES = 68
Air temp rounds:
1) 2885
2) 2890
3) 2878
Average = 2884
SD = 6
ES = 12
Difference = 95 FPS slower for the cold rounds.
That was more than I expected. If you throw away the odd ball cold round, the difference would have been about 66 FPS.
One issue is that I do not know the temp of the rounds pulled from the cooler. Though I would expect them to be under 32 deg. I just don't know how much the temp rose from the freezer to the range while in the cooler. I will test this again, as I really like the performance of the RL-17 in MY 300 WSM and will use a infrared thermometer to get the temp of the rounds before firing.
Also, in a thread from 2011, a member stated that he tracked the temp performance of RL-17 across 1000 shots and determined that the rate of change was about 2 FPS per degree change in temperature. Using that scale, calculates the temp of the cold rounds to have been 17 deg. when fired. Pretty cold.
Below is quote from the member.
coyotezapper
Well-Known Member
I have found most all of the extreme powders to be temp stable. That being said I have found other powders also to be temp stable including imr8208, rs magnum, us869, vv570 and rl33. I still like the RL powders - great velocities, and I try to develop my loads in the winter and then back off, and with a chrono develop summer loads that have the same velocity for practice shooting. I really liked the velocity that 7828 in my 7stw made but I could never get the accuracy I wanted so I went with h1000 and never tested its temp sensitivity.
Welcome to LRH and enjoy!
Here's from one of the good ole timers who has my utmost respect. I hope he's OK and post more and often ...
An excellent video from Mike Davidson ...
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Marble
Well-Known Member
The same guy who told me to do this, owns a gun shop and is a smith and has been for 30-40 years. He had a customer bring in a .300WBY mag that had shot a cartridge and froze the bolt to the gun. The guy was shooting factory ammo. Smith got the gun fixed up and then tested the same ammo from the same box and it shot fine. He asked the customer about the circumstances and the customer had his ammo on the dash of his truck in the summer heat, about 100 plus outside, inside a car that is probably 140+ degrees. He said the cartridges were hot to the touch when he shot his gun and froze the bolt.
Just interesting I thought.
Just interesting I thought.
I've chronographed thousands of rounds, often to establish whether a given load was stable. That started many years ago when an RL25 load I thought I perfected one morning blew off my extractor later that day when it was much hotter outside. Each load is different, no matter what powder is used. Generally, ball powders vary a lot, but uniformly. Not always. Ramshot Magnum in my 257Stw was very stable. H335 in a 308 load I had was unchanged over huge temperature swings. Retumbo is generally very stable, but can have an inverse change (higher velocity at lower temp). For me, H1000 is extremely stable. Same with varget. The only RL powder I use is 17, and in a 300 win mag, it varied a lot. But same batch is much better for my 6.5-284. Based on years of testing, I quit trying any other RL, alliant, VV or imr powders. For any precision rifle for hunting use, I generally start and end with varget, H4350, H1000 or Retumbo.
As noted in prior posts, not everyone gets same results. I've had certain caliber/bullet combinations with my favorite powders where they are unstable. That is sometimes the deciding factor between Retumbo and H1000. VV powders apparently win matches and set records, but for me, an accurate load at 50 degrees may be worthless at 30, so I don't use that powder anymore.
Could be case capacity and fill ratio. I believe, but cannot say for sure, that full cases are more stable. I also know a really smooth bore on a good barrel keeps velocity more uniform (based on lapping and breaking in barrels, I see that average velocity is pretty static, but ES shrinks). Sometimes poi reference is more important because some chronographs vary in different conditions, even if load is stable (that is a big problem I Montana in the winter because the sun is always at a low angle, and cheap chronographs don't like that).
While the freezing test is useful, if your gun heats up and you leave round chambered for any length of time, that powder will warm quickly.
Also consider what is most important. If you need first shot precision in extreme conditions, you need to know your load is stable, or how much it varies. I demand that in my long range hunting rifles. In sub zero weather, I sometimes keep a round in my pocket to keep it warm, just in case-- no matter how much I test, I still worry. But my K hornet, used for gophers only in the summer only needs to shoot well in those conditions. So, I can use lil gun, which meters so well I only every third round. But, I have no idea how fast or slow that round would be when it's 0 or 100, and that's ok.
In my experience, when a lot of people chime in that something is good or bad, probably some truth to it. When one person says something like a powder is bad, based on one load, I figure the result is more likely case specific.
As noted in prior posts, not everyone gets same results. I've had certain caliber/bullet combinations with my favorite powders where they are unstable. That is sometimes the deciding factor between Retumbo and H1000. VV powders apparently win matches and set records, but for me, an accurate load at 50 degrees may be worthless at 30, so I don't use that powder anymore.
Could be case capacity and fill ratio. I believe, but cannot say for sure, that full cases are more stable. I also know a really smooth bore on a good barrel keeps velocity more uniform (based on lapping and breaking in barrels, I see that average velocity is pretty static, but ES shrinks). Sometimes poi reference is more important because some chronographs vary in different conditions, even if load is stable (that is a big problem I Montana in the winter because the sun is always at a low angle, and cheap chronographs don't like that).
While the freezing test is useful, if your gun heats up and you leave round chambered for any length of time, that powder will warm quickly.
Also consider what is most important. If you need first shot precision in extreme conditions, you need to know your load is stable, or how much it varies. I demand that in my long range hunting rifles. In sub zero weather, I sometimes keep a round in my pocket to keep it warm, just in case-- no matter how much I test, I still worry. But my K hornet, used for gophers only in the summer only needs to shoot well in those conditions. So, I can use lil gun, which meters so well I only every third round. But, I have no idea how fast or slow that round would be when it's 0 or 100, and that's ok.
In my experience, when a lot of people chime in that something is good or bad, probably some truth to it. When one person says something like a powder is bad, based on one load, I figure the result is more likely case specific.
