Reloader 17 temp v velocity change

Discussion in 'Reloading' started by Aussie Powder Burner, Apr 26, 2011.

  1. Aussie Powder Burner

    Aussie Powder Burner Well-Known Member

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    I am developing a load for a new 6.5 x 284 with 139 lapua through 30" Krieger.
    Using RE17 and have an accurate load running 3060fps.
    My local temps are around 80F currently.
    Heading to NZ in 2 weeks with this rifle where temps will be from 25F to 50F.

    My question is what velocity loss should I expect at the lower temps?
    I am worried I may fall off the current accuracy node?

    Thanks in advance
    APB
    __________________
     
  2. Oliveralan

    Oliveralan Well-Known Member

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    Based on my experience (about 5000rnds of RK17 with 208 A-max, 190smk, and 190 VLDs in a .308 win F-T/R match rifle) RL17 is awesome for velocity, but like all PTSD double base powders, velocity swings with temperature... I'd you want to test it, put your rifle and ammo in the fridge, then shoot it over a chrono, that will give you an idea of velocity swings. I cannot speak for the 6.5x284.

    Another option would be to bring some ammo loaded at your current charge weight "X" and some at X+0.2gr or so. That should make up for most of the temp variation, a touch more powder will definitely bring you back closer to the node than just shooting the same load in potentially 55degrees lower temp.
     

  3. Aussie Powder Burner

    Aussie Powder Burner Well-Known Member

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    Thanks Oliveralan
    Rounds in fridge now
     
  4. Oliveralan

    Oliveralan Well-Known Member

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    no problem, while that will help simulate some of the change, if you, also cool your rifle. As barrel and chamber temp may also influence velocity.
     
  5. cfvickers

    cfvickers Well-Known Member

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    5-10 fps at 50F 20-30fps at 25F. I have tested at the temps you mention. My load work is mostly done at around 80F but my hunting is at 20-50F, I am pretty confident in telling you that. You may see far less difference. It is pretty stable until you get into high temps well above 90. Then it starts to get a little crazy. Velocity starts to fall under 35 or so. I have tested it with 130 VLDs 140 VLDs and 140 TBTLR berger bullets. I can't see where it would have much different effect with a scenar. What is your load? 50.5gr?
     
  6. Aussie Powder Burner

    Aussie Powder Burner Well-Known Member

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    Thanks cfvickers
    Need the experience of someone who has been there before - just what I needed.
    50.0 gr RE 17 = 3060fps with 139 Scenars naked
    50.5 gr RE 17 = 3100 fps but not as accurate

    I have something happening which I have never experienced before - a pressure spike on a clean barrel?
    I have actually loaded foulers at 48gr to fire on a clean barrel otherwise the bolt face ejector cut swipes brass form the case head. Once a fouler is run through I can go to loads such as the 50.5gr without pressure? This really messed with my head when i was running the barrel in [one shot then clean] plus chrono at same time.
    All my loads showed pressure and yet they were mild powder charges?!!
    Shot the rifle for the second time outdoors [ I have a 25m indoor range available] on Sunday at 900 yds to check come ups from the previous 600 yds zero of the first outing.
    The elevation data was 5 x 1/8 clicks low[xbal]. The next two shots after scope adjustment were both Super V which is a 5" centre on the 900 yd full bore target here. Both shots on same elevation line.
    I don't want to shoot targets too much because of the reputation for short barrel life with this cartridge and it seems the load is very close to optimum for accuracy. Total rounds so far = 50.
     
    Last edited: Apr 26, 2011
  7. Oliveralan

    Oliveralan Well-Known Member

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    Cfvickerd may very well be right, all my experience with temp instability is from developing at 60-70F then needing to readjust my charge as the temp climbed up to where I was shooting significantly less powder and still getting mild pressure signs when the rifle started getting hot after 15-20rnd strings in f-class. This was in 100F plus weather.

    Another thing is, at below freezing temps, CCI primers have been known to fail, I've had it happen a couple times.
     
  8. Aussie Powder Burner

    Aussie Powder Burner Well-Known Member

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    OK
    I am using BR2 as all my testing shows them to be lowest ES.
    These loads are single digit ES.
    What primer do you suggest at 30F or below?
     
  9. Oliveralan

    Oliveralan Well-Known Member

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    I cannot recommend any other brand of primer as I have never run any real tests comparing different primers in cold temps, but I will say that CCIs not working in the cold is something you'll hear about every now and then, I wouldn't call it common but it does happen.

    You could just keep your ammo in a coat pocket. My problem occurred after the ammo box was sitting in the snow with 19F air temp.
     
  10. Aussie Powder Burner

    Aussie Powder Burner Well-Known Member

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    Good advice - I will keep it in an inner pocket.
    I don't intend shooting a heap through this rifle as i have built it on a single shot Nesika for 800 - 1200 yd use.
     
  11. Oliveralan

    Oliveralan Well-Known Member

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    Good luck on your hunt!
     
  12. Aussie Powder Burner

    Aussie Powder Burner Well-Known Member

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    Thansk and thanks for your help.
     
  13. BradArnett

    BradArnett Well-Known Member

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  14. lisagrantb

    lisagrantb Well-Known Member

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    I have kept extensive records for almost a thousand rounds using RE 17 in a 260. when I run the numbers I get 1.9FPS change per degree change in temperature. I use 2 FPS/DEG in my computer and it works perfect