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  • Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    I'm still learning how to read OCW results. For extra practice (and snickers) i tried a 55gr bullet as well as a 75gr.

    I screwed up the charge marks on the paper with a pen but i was meticulous about the charge while loading. I relabeled them with good ol PAINT.

    55gr


    and 75gr
     

    Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    Looking at the 75gr (ignoring the pen marks and looking at the typed charge values...) it appears that 20.5 is my best OCW and scatter is 22.5.

    The 55gr, i'm going to say is.. looking like 22.5gr though i can't identify/verify it against an obvious scatter node.

    Any ideas/feedback from fellow OCW reloaders?
     

    iH8DemLibz

    When All Else Fails.
    Apr 1, 2013
    25,396
    Libtardistan
    I've always been amazed at what a difference a grain or two can make regarding accuracy.

    A one grain increase in my .243 Winchester reloads doubles the size of the group.


    Looking at your group, I'd retest for 20.5 grains and 22 grains. Then settle on the better of the two. Maybe increase your testing to seven or eight rounds each. To account for flyers.

    Keep your barrel as cool as possible to best replicate a cold barrel shot.


    IMG_8342.jpg

    IMG_8344.jpg
     

    Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    the load testing for my 300 win mag was "easy" to spot. I also did 0.3 gr instead of 0.5gr I also took A LOT more time doing the testing. I did today's test in one hour, the 300 win mag took me 5 hours to complete. for the same number of rounds.

    Thanks for the feedback. I assume you're only looking at group sizes not OCW groups because it seems you picked the tightest groups instead of the most consistent pattern of grouping even if they aren't as tight.
     

    Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    unless perhaps you meant make the entire range from 20.5 to 22.5 testing in 0.2gr increments.. hrm... might try that. take several minutes between shots (dont have a barrel temp reader thingy).

    should have thought about that. 0.5gr is a HUGE difference in a small volume case such as 223. Less of a deal breaker in the 300 win mag where volume is almost tripple that of a 223.

    ./sigh

    #lessonsLearned
     

    iH8DemLibz

    When All Else Fails.
    Apr 1, 2013
    25,396
    Libtardistan
    I wouldn't concern myself with .2 grain increments.

    You have two great groups based on two great loads as it is.

    I would retest for those two loadings only.
     

    Screwtop.243

    Ouch...that thing kicks
    Jul 7, 2011
    793
    People's republic of MD
    Did you shoot these "round robin" or shoot all of each charge weight into the same spot before moving on to the next charge weight? I've heard arguments in favor/against each method but have always stuck to the later method with my testing.

    The other method I've found interesting (but have not tried) is the one where you load 10 rounds in increasing charge increments (e.g., 22.0 to 25.5) and look for a velocity flat spot that theoretically should be centered around a node.
     

    iH8DemLibz

    When All Else Fails.
    Apr 1, 2013
    25,396
    Libtardistan
    Please excuse my ignorance, but what is this OCW and Node you guys are referencing?

    I was focusing solely on group size and charge weight.

    Looks like a chance to learn something new here.


    PS: Never mind. Looked it up on-line.
     

    Speed3

    Ultimate Member
    Aug 19, 2011
    7,816
    MD
    I think you might want to increase powder charge for the 75gr. 24gr of varget and 75gr hornady seems to be the trick. Obvouisly work yoir way up in 1% increments
     

    Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    Please excuse my ignorance, but what is this OCW and Node you guys are referencing?

    I was focusing solely on group size and charge weight.

    Looks like a chance to learn something new here.


    Google OCW 223 or OCW 308 etc etc. theres a great article/site about it. The short version is, it allows a bigger "window" to account for variables beyond control (weather, elevation.. etc etc).

    Example is my 300 win mag load. I use 64 gr and still get sub moa BUT.. i can put 63.5 up to 64.5 and still get the same "general group" location AND maintain 1 moa. So i reload for the middle of that group thus allowing me a greater window. It's not a big deal at 100-200 yards, but start pushing it out to 600-800 yards and you'll see it quickly.

    Once you get the OCW, you can fix the group size by seating depth and other things.. as long as your not WAY off.
     

    Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    Did you shoot these "round robin" or shoot all of each charge weight into the same spot before moving on to the next charge weight? I've heard arguments in favor/against each method but have always stuck to the later method with my testing.

    The other method I've found interesting (but have not tried) is the one where you load 10 rounds in increasing charge increments (e.g., 22.0 to 25.5) and look for a velocity flat spot that theoretically should be centered around a node.

    GREAT question. To each their own but, i shot each group before moving on to the next. The reason is, if the temp increases as you shoot. the middle group is always "warm but not hot".

    When i did my 300 win mag (Savage 110BA Stealth).. i shot all 5, one after another (bolt action) took about 1 minute per shot. Then waited the rest of the cease fire (about 20-25 minutes) before doing the next group. EVERY group had the same rate of fire and benefit of the same barrel temp start to finish.
     

    Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    I think you might want to increase powder charge for the 75gr. 24gr of varget and 75gr hornady seems to be the trick. Obvouisly work yoir way up in 1% increments

    In effort to keep in compliance with maryland gun powder limits, i'm trying to minimize the types of powder i have. Varget isn't in any of my other loads. I had 200 of these 75gr projectiles.. figured i would try w/ the powder i have on hand that's also listed in at least one manual.

    That being said, i've heard some people use varget and 4064 ALMOST interchangeably. Obviously, do your own research etc etc but so far, i'm happier with the 55gr as a ghog/fox/coyote load under 400yards. The theory of the 75gr was to push it out a bit more to 600y or so. To be honest, i've mostly just switched over to the win mag anyway though hHAHAHA.

    220gr ELDX out of a 300 win mag is.. devastating on a groundhog, even at 540 yards.
     

    Screwtop.243

    Ouch...that thing kicks
    Jul 7, 2011
    793
    People's republic of MD
    GREAT question. To each their own but, i shot each group before moving on to the next. The reason is, if the temp increases as you shoot. the middle group is always "warm but not hot".

    When i did my 300 win mag (Savage 110BA Stealth).. i shot all 5, one after another (bolt action) took about 1 minute per shot. Then waited the rest of the cease fire (about 20-25 minutes) before doing the next group. EVERY group had the same rate of fire and benefit of the same barrel temp start to finish.

    That seems like sound logic to me. That's pretty much what I do with all my rifles and lately have been testing with 6.5 X 47L and the 6.5-284 Norma. The only other thing I do (and I'll probably get flamed for this) is pull a bore snake through between 5 shot groups. Maybe I'm supposed to let the bores foul but with consistent .25 to .38 MOA and less than 1 minute vertical dispersion out to distance, I figure it's OK for crop damage duty out to 550 or 600 where I hunt.
     

    Pinecone

    Ultimate Member
    MDS Supporter
    Feb 4, 2013
    28,175
    Looking at the 75gr (ignoring the pen marks and looking at the typed charge values...) it appears that 20.5 is my best OCW and scatter is 22.5.

    The 55gr, i'm going to say is.. looking like 22.5gr though i can't identify/verify it against an obvious scatter node.

    Any ideas/feedback from fellow OCW reloaders?

    Scatter should be 1.5% more or less than accuracy node.

    So 1.5% higher than 20.5 = 20.8, 21.1 for next accuracy, then 21.4 for scatter.

    Your steps are too large for OCW. OCW should increase 0.5 - 1% per step.

    So starting at 20.0, you should use increments of 0.1 - 0.2 grains.
     

    Pinecone

    Ultimate Member
    MDS Supporter
    Feb 4, 2013
    28,175
    GREAT question. To each their own but, i shot each group before moving on to the next. The reason is, if the temp increases as you shoot. the middle group is always "warm but not hot".

    You need to shoot OCW round robin.

    This evens out affects of temp and of fouling.

    And you should be running at least a full minute between shots to reduce heating.
     

    Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    Scatter should be 1.5% more or less than accuracy node.

    So 1.5% higher than 20.5 = 20.8, 21.1 for next accuracy, then 21.4 for scatter.

    Your steps are too large for OCW. OCW should increase 0.5 - 1% per step.

    So starting at 20.0, you should use increments of 0.1 - 0.2 grains.

    i was using a premade excel spreadsheet which only indicated to pick a value from 0.2 - 0.5 grains. It didn't give an explanation of where these come from. the 0.5 - 1% STEP makes more sense than grain amount.

    My previous happy spot was at 22grains so maybe i'll go 2% under that and build up from there. To confirm the scatter.

    Thanks again!
     

    Moorvogi

    Firearm Advocate
    Dec 28, 2014
    855
    You need to shoot OCW round robin.

    This evens out affects of temp and of fouling.

    And you should be running at least a full minute between shots to reduce heating.

    Round robin would affect fouling, i totally agree. I can't see how it affects the heat though. I've never confirmed it with a heat sensor but.. my thought is this... every bullet shot heats the barrel. Let say it heats it by 1 degree every shot. This is fine, as long as it also COOLS.. the same amount every minute. If this doesn't happen, by the time you get to the last shot of the set, it's hotter than when you started.

    I guess one solution is to get a heat gun/sensor and document the temp only shooting when it's the same temp each time?? Or recording two temps, one for a cold bore and one for warm bore. Which the round robin will be faulty then.

    if shooting round robin is to normalize temperature, the only way it makes sense to me at the moment is to shoot EVERY shot at the same temp (cold bore).

    again, i value feedback/ideas but i also feel that there should be supporting documentation or logic behind it.
     

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