Need Coaching Interpreting Range Data

Discussion in '6PPC, 6-6.5x47, 6XC, 6 Rem, 243' started by Badbob, Jan 29, 2018.

  1. jimmymac

    jimmymac Silver $$ Contributor

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    What threw me off is when you said your rear bag was a brick bag. To me, this is a brick bag:

    brick.jpg



    First thing I thought was how is shooting free recoil possible with a brick bag.
     
  2. Badbob

    Badbob

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    Folks, went out to the range yesterday and worked on load development. Attached is my target. I need your help and your opinions about where to go from there. To recap, I changed primers to CCI450 and loaded .010" off the lands. Conditions were 50 degrees and wind was 0-3mph. Yes, I used wind flags. Also, my crappy chrony kept erroring out so my velocity data is spotty.

    Best groups: 39.4gr @ .366"; 40gr @.374"; 40.3gr @ .387"

    38.8 had consistent velocities ERR; 2952, 2963
    39.1 ERR; 2963, 2963
    39.4 ERR, ERR, ERR

    To date my best group is .361 38gr H4350, BR-4, .005" off the lands.

    Sorry, I meant .344" 42 grains H4350, BR-4 .005" off the lands. But too fast for PRS shooting.

    So what are your thoughts? What is the gun and what is me? Where shall I go from here? Thanks!
     

    Attached Files:

  3. Badbob

    Badbob

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    First target group average was .658" and the second target group average .535"

    So, either I got better at shooting, or the CCI450s plus being .010" off the lands slightly improved my overall average.

    Many thanks, BB
     
  4. kyreloader

    kyreloader Gold $$ Contributor

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    In my opinion, both targets show a scatter node at 39.4/39.5g. If so, the best node should be 1.5% above and below that node, hence 40/40.1g and both targets support that as being the node. I would do my OAL test at that charge. Remember, this is a PRS rifle, so I would be satisfied with my precision of this load and just start practicing. Your position and wind reading ability will mean more points then 0.1 or 0.2 MOA in your load development.

    Flame suit on.
     
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  5. kyreloader

    kyreloader Gold $$ Contributor

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    41.2/41.3g would be the upper node and I think your first target jives with that as well. Do OAL test at 40.1g and 41.3g and see which one shoots best. Load up and practice.
     
  6. Badbob

    Badbob

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    So, then would I do .005 increments? 020, 015, 010, 005, touch, 005 in, 010 in ?

    thanks for the suggestion! I agree, time to settle on a charge and start practicing. I have 175 cases that need fire forming!
     
  7. Drop Port

    Drop Port

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    This, ^ I might have missed it but it appears you changed seating and primers, if so I would do one change at a time to isolate results. Looking at what you have I would put $ on it that 41.3 will suck in with seating depth. Let the load tell you not any of us. My 6.5 x 47 shoots Hybrids right where most would rather not have them (just touching) but if I hadn't tried it I would never of known how extremely accurate this combo is.
     
  8. Badbob

    Badbob

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    Ya, I switch both . . . see advice given above. Probably should have just left the seating depth the same. Thanks
     
  9. kyreloader

    kyreloader Gold $$ Contributor

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    Since this is for PRS, I wouldn’t load into the lands. Start 6 off and go by 3s, so 6, 9, 12, 15, 18, 21 off. I bet you find a clear seating depth node and if shot with both charges, a clear powder charge node winner too!

    My thoughts.
     
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  10. fredo

    fredo Silver $$ Contributor

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    My 6x47L load with 105 Hybrid jumped .015" is 39.3H4350, CCI450. Nets 2998fps from 23" Bartlein 1:8, with low ES. There's a bunch of online 'proven' loads within a couple tenths +/- of there to illustrate that ~39.5 'node range' is a good place to narrow down toward...

    You have gotten excellent info so far, just wanted to share some data to let ya know you're "in the ballpark" with your 39.4gr load.

    IMHO, that ~1.5gr 'higher node' is a bit more than I'd care to push the x47L, despite it's noted case strength. Your call on whether or not to run it up there?

    Good luck and good shooting!
     
    Last edited: Feb 5, 2018
  11. reubenski

    reubenski

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    You need to buy a Magneto speed chronograph. Or maybe Adam MacDonald's Two-Box Chrono. If you don't want to spend the money then develop your load based purely on precision and after shoot a group at 1000 to figure out your velocity. After shooting and recording the data required at 1000 use the published Litz BC and adjust the MV in your ballistic computer until it agrees with your proven elevation correction. That is your effective muzzle velocity.
     
  12. dedogs

    dedogs

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    Surprised no one has said anything about that saggy rear bag. I'm not a PRS shooter, but I would never use a bag that saggy on a bench set-up and expect good groups. The ears also look like they need more fill. I do not use heavy sand in the ears of my rear bag, play sand seems to work better. dedogs
     
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  13. wholman

    wholman

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    40 ish looks good to me then play with seating 2 to 3 th at a time.
     
  14. Badbob

    Badbob

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    I agree . . . I think I will firm up the bottom and change out the sand in the ears. I don't think I'm getting the stability I need. Thank for pointing this out. BB
     
  15. Badbob

    Badbob

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    are the hobbist chronographs like the Caldwell even worth the time? thanks for the suggestion to work up an "effective muzzle velocity. I've shy'd away from the Magneto because it is reported that it effects grouping and load development work. BB
     
  16. reubenski

    reubenski

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    I would not recommend a cheap Chrono. It is just 50% of the money you could and will eventually put in a quality unit.

    The Magneto doesn't inhibit load devlopment. It does change most barrels POI and often group size(it actually shrinks the groups of my first 6Dasher barrel). Some do OCW tests with the Chrono on, arguing that the changed POI is consistent so the elevation deviation can still be evaluated. I do not. You can still measure MV increase, SD's, and ES's for the same analysis of node using a MS. Worst case you just can't do it while also shooting for groups.
     
  17. Badbob

    Badbob

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    So basically I have to keep my load development and my velocity analysis separate. I'm concerned that it will effect barrel harmonics and therefore effect your node results. I could be overthinking it, though.

    so what other options for a Chrono are out there besides a Caldwell or a Chrony or the Competition series? BB
     
  18. reubenski

    reubenski

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    It really depends how you do load devlopment. There are so many preferences. It would be hard for me to give a yes or no answer without hanging oit at the range with you for an afternoon.

    The only Chrono's ..I... would consider purchasing are the MS, the 2 Box, and a Labradar. Pretty much in that order too. Do a light Google search on Bryan Litz's Chrono comparison comparison. It outlines accuracy and consistancy of various models.
     

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