R-25 temperature variation

Discussion in 'Reloading' started by Cheyenne 1, Jan 1, 2012.

  1. Cheyenne 1

    Cheyenne 1 Well-Known Member

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    I was just started making some loads for my newest rifle. A remington 700 in 257stw. Using remington brass, CCI magum primers and RL-25. Started out with 77 grns, ended up at 81. Problem seems to be with the larger powder charges are really sensitive to temperature change. It is a little cold here, about 14F.
    I didn't think the last couple of loads were what they should be. I put the last 2 in my pocket to warm them up and both were exactly the same speed 3875, the ones before at outside temp were at 3760. That seems like way too much of a spread.
    I have read (Now) that the r-25 will do this. Anybody else have this problem? What about the Hodgon extreme powders, they claim that it will not change with temperature?
    Where I hunt it can go from 50F to 40 below 0.
    Thanks
     
  2. jayran

    jayran Well-Known Member

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    I use rl25 in my 257 wthby accumark tried the same thing but didnt experience the problem. I had read the same thing so had to try, from what i remember thru the chrono i didnt see more than 40fps. I will have to try it again, because I was just reading another post with similar concerns???
     

  3. royinidaho

    royinidaho Writers Guild

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    With RL-22 in a lowly 270 Win I dropped from 3200 MV @ 70* to 3070 @ 15*. (130 FPS)

    The RL powders are quite temperature sensitive.

    I'm not bothered by the temp sens. as long as I know how much its worth.
    BTW all powders are temperature sensitive, some more than others.
     
  4. Len Backus

    Len Backus Administrator Staff Member

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    Roy, I wonder if that much velocity and pressure difference changes barrel harmonics and therefor POI or even group size.
     
  5. Derek M.

    Derek M. Well-Known Member

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    It did not in my 300 RUM. I worked up loads in Ohio during late summer when it was about 80-85 degrees and hunted in Wyoming and Colorado when it was in the 20s and 30s. Granted, I didn't shoot far (under 400 yards), but the bullets hit where I wanted them to.

    Hodgdon Extreme gets the nod from the bulk of reloaders for temp concerns where highly suspect powders like Alliant lose their luster due to repeated experiences of temp sensitivity.

    My solution is to work up loads during the time of year that will be on par with the climate I plan on hunting. Fortunately, I do this here in Ohio where it can get just as cold as it does when and where I hunt out west. So far, problem solved.

    Reloder powders produce some of the most consistent and best groups I've ever had, not to mention best velocities. No way I'm not going to use them any longer like a lot of guys do when they ultimately narrow down all choices to Hodgdon.
     
  6. Derek M.

    Derek M. Well-Known Member

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    I think I'm going to migrate to all magnum primers in my 270s. I have good loads with both 210M and 215M and I'm thinking (could be wrong), that a hotter fire to start could reduce velocity changes.

    I think a 215M might be the ticket with the slower powders I use such as Re22, and H1000.
     
  7. royinidaho

    royinidaho Writers Guild

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    Len,

    You betcha on all of the above.

    The good thing is that for my use the Winny is relegated to less than 300 yard opportunities in the winter. For yotes and mule deer in the back yard area shot distances are nearly point blank, if I'm stealthy.:)

    Derek M.,

    I agree. Especially when shot opportunity is under the 400 yard mark.
     
  8. Cheyenne 1

    Cheyenne 1 Well-Known Member

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    Well in my stw 120 fps difference results in 5.5 inches difference at 550 yards. The problem is what happens if your shells end up on the dash of the truck and are at 100f? I will try some different powders and post the results. I picked up some ramshot today, and will get some retumbo (they were all out till next week).
    I have shot Rl 22 and 25 for years. For the most part it is accurate and always seems to be faster than most other ones. I guess I never tryed across the chronograph in the colder weather.
     
  9. Michael Eichele

    Michael Eichele Well-Known Member

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    I read all the time about this and it baffles me. I have never seen this at all. In fact I have seen the opposite. I dont know if there are factors that we are not aware of that come into play such as load density, or high/low pressure loads, etc....but I have tested RL15, RL19 and RL25 in several different guns/calibers from 0 degrees to 80 degrees side by side leaving loads outside all night and regulating others in my house and warm vehicle and have always seen very consistent numbers (within 25-40 FPS) and in one comparison, the velocity increased a bit with the cold cartridges (????). I know of other that have performed similar comparisons with similar results.

    On the other hand I found VVN540 to be fairly sensitive. I documented the spreads from -2 degrees, 55 degrees and 80 degrees incorporated this factor into my ballistic calculator. I set it up for a baseline. When I enter the current air temp, it adjusts my velocity accordingly (the beauty of developing your own software). The groups and suprisingly, my 300 yard zero did not change (the beauty of harmonics).

    Regardless, I hear lot of comments about RL powders and they always seem to contradict.
     
  10. lever-hed

    lever-hed Well-Known Member

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    Mike,
    I'm gonna agree with you on this, always hear this stuff and it doesnt really figure to me.. I've used Reloader and Hodgdon extreme powders in both hot humid and extremely cold conditions and I dont see a huge desparity( i get good results with both al yr round). At least not enough to change my entire loading.. and If so, I would make a summer load and a winter load with the same bullet.. But so far I have not been so inclined to do that.
    Different chrono's have diff operating temps and , when you go from hot humid to extreme cold, the aire is drier, it seems I can group better during the winter, I don't worry about the velocity for the most part.. further, if I was in a match in 5 F degree weather..I wouldnt be, if ya know what I mean...
    Anyways thats my 2cents on it..
     
  11. Greyfox

    Greyfox Well-Known Member

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    I have had good success with the Hodgdon extreme powders, namely, h4831 a n Retmbo. I have used them from 0-80 degrees. I have had some issues with temperature with the Reloader powders.
     
  12. Cheyenne 1

    Cheyenne 1 Well-Known Member

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    Well I tried this today. There may not be as much of a difference as I first thought there was. Here is what I tried today.
    I loaded 6 bullets with 3 different powders Ramshot, H-1000, and RL-25, I used 79 grains of each kind of powder with a 100 grain bullet. I took 3 of each load and put them in the freezer overnight. The other ones when I went out to shoot I left them in my inside jacket pocket. The temp today was just below freezing. The average for 3 shots are as follows.

    Ramshot 3581 warm and 3574 cold. I did notice that the ramshot had a couple of hangfires.

    RL-25 3741 warm and 3724 cold

    H-1000 3686 warm and 3724 cold, the only problem was I had a little chrono error and it only recorded 1 shot, so the cold was not really an average.

    I will try this with some retumbo as soon as I can find some.
     
  13. fatrack

    fatrack Well-Known Member

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    I believe all powders are temperature sensitive.

    Instead of introducing potential errors by using a chrono repeat your temperature experiment but shoot at 500 yards and check the difference in drop. Shoot one cold and one hot and see what kind of spread you got.

    I live in a cold place and if you don't account for temperature you won't hit where your aiming.