RL33 Temperature Regression Thread

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by MontanaRifleman, Feb 12, 2014.

  1. MontanaRifleman

    MontanaRifleman Well-Known Member

    Messages:
    6,068
    Joined:
    May 21, 2008
    Thought I would start this thread to get some good collective data on RL33 stability or temp sensitivity. Would like to get some results from others as well (collective data).

    How did you go about your testing and what chrony did you use, conditons, etc.

    The other day I went to the range to do some load development and while there shot some temp test rounds through the 300 RUM and 6-284. Abient temp was 20* and did some cold soaking to get the cold temp rounds down to that temp. I put the warm loads on the floor of my vehichle and maintained 75* after loading them inside at a temp of ~ 70*. Shot the cold rounds first letting the barrel cool between shots, then right after the last cold shot, I fired the warm rounds at a faster rate to keep the barrel warm. Chrony used was a MagnetoSpeed

    300 RUM results, 230 hybrid Targets over 96 gr of RL33, 27" 5C Broughton.
    Note: Warm loads showed signs of excessive pressure

    Cold rounds, 20*..... 3101, 3082, 3095.. Avg, 3092
    Warm rounds, 75* .. 3170, 3142, 3158.. Avg, 3157
    Avg fps/degree diff = 1.18 fps/degree

    6-284 results, 105 Hybrid targets over 60 gr RL33, 26" 5C Broughton (low pressure load)
    Note: First cold round was out of a freshly cleaned bore and showed signs of higher pressure, but not excessive. Could have been some left over cleaning residue in the bore.

    Cold rounds, 20*.... 3342, 3302, 3287.. Avg, 3310 (without first shot 3295)
    Warm rounds, 75*.. 3340, 3309, 3331.. Avg 3327
    Avg fps/degree diff, 0.31 fps/degree
    Avg diff without 1st shot, 0.58 fps per degree

    I plan to do some more testing with the RUM when I get some new brass. I have some test rounds loded in the 6.5 WSM and will fire a few more through the 6-284 as well.

    If you have any data to add, please do.
     
  2. AZShooter

    AZShooter Well-Known Member

    Messages:
    2,075
    Joined:
    Dec 12, 2005
    Talk about testing for MY rifles! I shoot both of those chamberings with same bullets and also use RL-33. Interesting how the 6mm-284 didn't change much.

    Looking forward to more of your testing.
     

  3. Max Heat

    Max Heat Well-Known Member

    Messages:
    385
    Joined:
    Feb 26, 2012
    I know that 25 and (especially) 22 can be very finnicky/temperamental when it comes to temperature. But being that my inital testing has shown both of those formulations to be (way?) too fast for my new 32" 7RUM barrel, it looks like I'm all in with 33, at least until they come out with the RL30 formulation (if that ever happens). Consider this to be the 1st (that I know of) request for RL30, Alliant!

    I only have hot-temperature RL33 load data for the factory rem 26" barrel. So I'm unable to directly compare to the new barrel. But I am definitely seeing the potential of 33. Nice 139SST groups with 100gr, and going to be trying 102.5 and 105 (my self-imposed limit) soon - depending on how much more snow we get hit with here today!

    I want to avoid a replay of the "develop-your-max-loads-during-peak-cold-and-they-will-be-too-high-pressure-when-peak-hot-season-comes" scenario. But RL33 does seem to be very forgiving, or non-finnicky, when it comes to giving-or-taking a couple of grains. I HATE to see that is as bad as your testing shows, with regard to temperature though. I wouldn't have figured that. But good to know, as I won't have any such data of my own until this summer.
     
  4. MontanaRifleman

    MontanaRifleman Well-Known Member

    Messages:
    6,068
    Joined:
    May 21, 2008
    It might be that since the warm 300 RUM loads were apparently near max that there was a pressure spike. When new brass gets in I'll do some more testing to confirm or contradict.
     
  5. MontanaRifleman

    MontanaRifleman Well-Known Member

    Messages:
    6,068
    Joined:
    May 21, 2008
    Not really enough data to come to any strong conclusions one way or another. As mentioned there could have been a pressure spike due to an apparently max load in the RUM. The 6-284 results are good IMO but also still need some more data to confirm the results.

    Hoping some other guys will get out there and share some results.
     
  6. Max Heat

    Max Heat Well-Known Member

    Messages:
    385
    Joined:
    Feb 26, 2012
    I don't mean to hijack the thread, but I am curious as to what kind of sign your RUM shows you when pressure is exessive. Pressure sign from my R700 7RUM is COMPLETELY different from what my S110 (7RM) shows. I'd like to know if it is a rem thing, or a RUM thing, or neither. What I'm referring to in particular is what I call primer flow-back (into the bolt-face FP hole). Many refer to it as a "cratered" or "splashed" primer. I can't remember the sav EVER showing that sort of sign.
     
  7. MontanaRifleman

    MontanaRifleman Well-Known Member

    Messages:
    6,068
    Joined:
    May 21, 2008
    PM sent
     
  8. Max Heat

    Max Heat Well-Known Member

    Messages:
    385
    Joined:
    Feb 26, 2012
    OK, thanks.

    But getting back on topic, I find that 33 seems to be ALOT slower & way more "stable" than 25, the next fastest in the current RL series line-up. The temp instability doesn't make a whole lot of sense for such a powder. Like said, more data is need before any solid conclusions can be drawn. But 33 is exhibiting un-expected behavior for me also, but in a different way. It's starting to look like a very strange animal!

    I've only fired one 5-shot group with it so far, out of my new [long] barrel. So the data is scarce in MY scenario also. The velocity readings were anything but tight. And that probably explains why the [best 4 shots, out of 5] group did 1/2moa on the horizontal plane, but only managed 1moa on the vertical.

    Here are the actual #s:

    1. error
    2. 3486
    3. 3379
    4. 3570
    5. 3501

    There is almost 200fps between shots 3 and 4. That seems pretty crazy. It's hard to believe I even achieved 1moa vertical, with THAT kind of variation. I weighed each charge individually, to boot! Maybe I screwed up somehow on that, as it is the only "reasonable" explanation. I have the next 5 rounds loaded to within 4/100 of 105gr, so we'll see how that goes. But we just got dumped with another foot of snow here since yesterday, on top of what was already laying, so not sure if I'll make it to the range today or not.
     
  9. MontanaRifleman

    MontanaRifleman Well-Known Member

    Messages:
    6,068
    Joined:
    May 21, 2008
    Yes, RL33 is a lot slower than 25 and hopefully more stable.
     
  10. Outlaw6.0

    Outlaw6.0 Well-Known Member

    Messages:
    3,006
    Joined:
    Feb 18, 2010
    What kind of chrony are you using? I would bet your weird velocity stem therein.


    t
     
  11. Kiwi Greg

    Kiwi Greg Well-Known Member

    Messages:
    368
    Joined:
    Nov 14, 2008
    It has been noted else where that RL33 doesn't like the bullets to jump far.

    So magazine length rounds can be problematic.

    It really upsets the ES, less than 20 thou jump apparently is best.

    I haven't noticed any issues but none of my rounds jump more than 10 thou.
     
  12. MMERSS

    MMERSS Well-Known Member

    Messages:
    912
    Joined:
    Feb 5, 2013
    I load developed my 300 RUM around 30 degrees. No pressure problems and great performance with RL-33 from temps in the mid 20s to mid 50s. This past week I blew a primer with temps around 0. I usually store the ammo in my pocket to keep them near the developed temperature. Three rounds were taken out of my pocket and placed next to the gun. By the third round after some time sitting outside the round blew a primer with a hard bolt release. It appears RL-33 may be subject to overpressure in extreme cold temperatures just as much as extreme hot temperatures. FWIW something else to consider.
     
  13. MontanaRifleman

    MontanaRifleman Well-Known Member

    Messages:
    6,068
    Joined:
    May 21, 2008
    Interesting, I have shot it in the 6-284, 6.5 WSM and RUM in temps 2-7 and had no problems. What did the other 2 rounds show? Any ejector marks or other signs?
     
  14. MMERSS

    MMERSS Well-Known Member

    Messages:
    912
    Joined:
    Feb 5, 2013

    Nothing. Just this round however the other two didn't sit outside near as long as the third. With virtually no freebore I'm not too eager to test the extreme cold temps again. I'll just ensure the ammo temp stays above 20 before firing. Not really an issue for me now that I know what could happen otherwise. I'm not enthused about the small jump but it seems to be the only luck I have found using RL-33 to the full advantage of speed and low ES. I haven't found a combo yet outside RL-33 that will push a 230 Berger near 3200 FPS with ES in the low teens. I'll probably drop the charge by 1 grain for piece of mind anyway.