Need help deciphering OCW test results

Discussion in 'Reloading' started by dog caller, Mar 5, 2006.

  1. dog caller

    dog caller Well-Known Member

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    I tried the OCW today with my 243. I already have a great load for this rifle using the 85 TSX and AA3100. I would like to find a better load using Varget since it is less temp. sensitive and overall more stable. All rounds were in new brass (meticulously prepped), GM210M primers, 85g TSX's and 2.661" OAL (.020 off of lands).
    The measurements I am listing are from the center of the 3 shot group POI to the center of the target POA. I waited anywhere from 3 to 5 minutes between shots and fired 2 barrel fouling shots before beginning my test

    Results are:
    1. 39.3g Varget 1.550" high, .975" left, 3200 fps, ES 70, SD 38
    2. 39.6g Varget 1.273" high, .605" left, 3207 fps, ES 23, SD 11
    3. 39.9g Varget 2.022" high, .595" left, 3238 fps, ES 55, SD 27
    4. 40.2g Varget 2.065" high, .410" left, 3252 fps, ES 64, SD 34
    5. 40.5g Varget 1.735" high, .250" left, 3292 fps, ES 72, SD 41

    Loads 3, 4 and 5 share a common POI that is .402" center to center but their average group size is 1.097". Load 2's POI is the farthest from any of the others but was a nifty little .311" group.

    Do I choose load 4 because it is the middle of the 3 loads that had the POI's closest to each other and try to tweek the seating depth to close the groups up or do I choose load 2 with the tiny little group and see if it was a fluke by trying to duplicate the group? I know that option 1 is correct but I just can't get that .311" group out of my mind. Help!
     
  2. green 788

    green 788 Well-Known Member

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    dog caller,

    That TSX is a solid copper bullet I believe...

    With Varget, the max with 85 grain bullets in the .243 win is around 38 to 38.5 grains (depending on whose data you're looking at).

    It might be that you're too high with the powder charge. Did you have any pressure signs?

    Generally a 22" .243 win barrel will give just over 3100 fps with 38 grains of Varget and Sierra's 85 grain BTHP. I don't know how the Barnes bullets will compare to that, but I do know that they're harder, which will usually drive up pressure just a bit.

    Can you post a photo of your target? Or email it to me and I'll post it? That would help a lot...

    Take care, and stay in touch--we'll figure it out. /ubbthreads/images/graemlins/smile.gif

    One more question: What rifle are you using, and what barrel length? Thanks,

    Dan
     

  3. dog caller

    dog caller Well-Known Member

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    [ QUOTE ]
    With Varget, the max with 85 grain bullets in the .243 win is around 38 to 38.5 grains (depending on whose data you're looking at)

    [/ QUOTE ]

    Dan,
    Barnes manual #3 lists the maximum charge weight for a coated X bullet at 39 grains of Varget. They don't list a Varget load for the regular X bullet. Other powders that are listed for both the XLC (coated) and XBT (non-coated) show that the maximum is always two grains more for the XLC. Knowing this and knowing that Barnes suggests the TSX can handle one or two more grains than the regular XBT, I deduced that a safe starting load for the TSX would be about the same as for the film coated XLC X's. On previous attempts to find a load (the old fashion way)for the TSX and Varget, I started with 36 grains and worked up (in increments of .3 grains) to 39 grains. None of these shot particularly well but showed no signs of pressure. After joining here and reading about the Ladder and OCW tests, I thought I would give the combination another try. Since I showed no pressure signs at 39 grains, I just started there to begin the OCW test.

    [ QUOTE ]
    It might be that you're too high with the powder charge. Did you have any pressure signs?

    [/ QUOTE ]

    I carefully checked each round for signs of pressure and found none.



    [ QUOTE ]
    Can you post a photo of your target?

    [/ QUOTE ]

    I'll try....



    [ QUOTE ]
    One more question: What rifle are you using, and what barrel length?

    [/ QUOTE ]

    It is a 22 inch Savage 16FLSS with a 1 in 10" twist. Also, all rounds were shot over a Prochrono Digital chronograph set 10 feet downrange from the muzzle.

    Thanks, Dan, for taking the time to help me with this. Let's see if this picture thingy works /ubbthreads/images/graemlins/grin.gif

    [​IMG]
     
  4. 41mag

    41mag Well-Known Member

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    Just for the sake of discussion, you say,

    "Load 2's POI is the farthest from any of the others but was a nifty little .311" group.

    (2.) 39.6g Varget 1.273" high, .605" left, 3207 fps, ES 23, SD 11 "

    Does this pose problems?

    When I do this sort of test, I am not overly concerned with the POI-vs-POA to an extent. I look for just what your target is showing with "Group #2", nice tight group showing low ES & SD.

    In my mind and if it were me, I would load up some more of "Load #2", adjust the scope, shoot say 10 over the chrono for groups, and more than likely, if things were similar, go to that load.
     
  5. green 788

    green 788 Well-Known Member

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    DC,

    Thanks for the photo. That helps illustrate things...

    That number 2 group will not be repeatable. If you look at it this way, all it's going to take is a slight pressure drop, and it's shooting just like group number 1. Or a slight pressure increase, and it'll be shooting like group number 3. A pressure drop or increase can be caused by an odd brass case, hot or cool primer, very cold or very warm weather, etc.

    I've got to say--based on your results with Varget between 36 and 39 grains (which you say were not good) and the results we see here--this powder/bullet combo is probably not going to work. This is assuming that your rifle is shooting tight with the AA powder you mention. If you're not getting .5" groups at 100 yards with any other bullet and/or powder, then I would look to scope and mount issues as the possible culprit. Also, see if the bore is heavily laiden with copper--another possibility.

    If, however, the rifle is indeed shooting well with other powders or bullets, then I would abandon the idea of using the Varget with these particular bullets.

    You might try 38.0 grains one more time. That charge should do much better than groups 1, 3, 4, and 5. I think that group 2 is a fluke, but you may want to try it again to see what happens.

    Too, based on the "scatter group," which I believe is group number 3--you should find another accuracy node at 40.8 grains. That's well over max in most books, but if you're not getting any pressure signs at 40.5, you should be alright to test 40.8 grains.

    What lot number is the Varget you're using? (Should be on an orange label on the bottom of the can, or on the main label if it's a newer lot).


    Dan
     
  6. dog caller

    dog caller Well-Known Member

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    [ QUOTE ]
    This is assuming that your rifle is shooting tight with the AA powder you mention.

    [/ QUOTE ]

    Dan,
    I've included a couple of scanned targets which were shot earlier this year. All were using the 85 TSX, 44.5g of AA3100, Federal GM210M primers, Winchester brass and 2.661 OAL which puts this bullet .020" off of the lands. Average velocity is 3081 fps.
    [​IMG]

    This one was .457" center to center, shot at 100 yards

    [​IMG]

    This one is .464" center to center, also shot at 100 yards.

    [​IMG]

    This one measured .997" and was shot at 300 yards.

    [​IMG]

    This 1.007" group was also from 300 yards.

    [ QUOTE ]
    Also, see if the bore is heavily laiden with copper--another possibility.

    [/ QUOTE ]

    I use Sweet's 7.62 after every 15-20 rounds, repeating the wet/patch scrub and the dry patch wipe until no color remains. In fact, my wife tells me I will scrub the bore out of a gun way before I will be able to shoot it out of one /ubbthreads/images/graemlins/grin.gif
    [ QUOTE ]
    What lot number is the Varget you're using?

    [/ QUOTE ]

    The lot on the current can of Varget I'm using is #10609034076.

    Dan, overall I agree with you on probably not being a good combo. I will try to duplicate that #2 load because I feel like I was on my game when I shot it. Conditions were good, I was comfortable, good surprise trigger breaks.....
    I can normally tell when I pull one or whatever and the only time I felt that I might have shanked a shot was the second shot on target number 3 (the low shot). Like I told you in my e-mail, I really don't need a load for this bullet as I already have one that shoots extremely well. I just kinda like Varget and wanted to find a load with it. Plus, I've been wanting to try out the OCW method and this seemed like a good opportunity /ubbthreads/images/graemlins/wink.gif

    I may play with some loads in the 38g range again and see if I can tweek something a little better than the originals were. Out of all of the loads I shot from 36 to 39 grains, 37.8 and 38.1 showed the most promise. Both of those were between .8" and 1". That would make sense if you feel like there was a node there. I really appreciate you taking the time to help me read this right. I'll buy ya a beer sometime!!

    DC
     
  7. green 788

    green 788 Well-Known Member

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    Those AA3100 groups are fantastic. It is obvious that you, and your rifle, can shoot. /ubbthreads/images/graemlins/wink.gif

    Do post back on the 38 grain Varget load with that bullet. I'd be interested to see how it does...

    Thanks,

    Dan
     
  8. green 788

    green 788 Well-Known Member

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    Just a note to clarify something...

    Mike/TX and I communicated off line, and he correctly points out that there will be times when you find a very narrow "niche" where the group comes together. One small graduation on either side of that niche will find poor accuracy once again. There can be many reasons for this, which aren't necessarily pertinent to this thread.

    My own philosophy is that it's best to find a powder charge range, at least 2% wide, where the groups stay put. That allows for a little more latitude with case volumes and powder lots, etc. But Mike/TX's point is well taken.

    Dan
     
  9. 41mag

    41mag Well-Known Member

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    Basically what I reported to Dan was that, I have several rifles which will duplicate exactly what your target shows. While this is definately not representitive of the vast majority of loads and the rifles which shoot them, it does happen.

    As Dan mentions, when doing this sort of testing, you will generally see, some grouping which will gradually trend smaller towards the nodes or sweet spots. My point above was that, sometimes however, you see such results as 1.5" groups dropping into .5 groups as well. Normally your groups will go from 1.5" to 1", then so on and so on. Does this mean that you should abandon the use of a load similar to what you have in group #2, not necessarily, as it might be fine. However, it does warrant more testing, as I mentioned.

    The rifles I have, which exibit the similar tendencies of your groups, will shoot several loads constantly into 1" to 1.5". However they will drop under .5 with only one load combination of bullet and powder. These particular loads, for these particular rifles, have been repeatable through the years, in varied conditions and through different lots of components. With the changing of component lots, the load might vary a couple of tenths one side or the other of the original powder charge, but get past this particular area, and the groups spreads out drastically.

    I agree with what Dan say's on this type of testing. It is always best to have a combination which has a more visable or defined sweet area. This in most cases allows for subtle changes to occure and still maintain the intergity of the load and any ballistic data one might have developed for it. However it can be, as I mention, repeatable within a narrow range as well.

    There is merit, from what I have seen through the years, for both the OCW and the Ladder test. In fact I generally incorporate both into my load development. I guess you could call it a hybred. I generally set up a half dozen pasters on a target, and set up my seating dies to be somewhere right at the MAX OAL to allow the rounds to fit the magazine. I then go about shooting somewhere from 3-5 shots at each dot over the chrono and work my way up, with a particular powder. I generally try to get 80%+ densities on my loads so this helps to narrow the choices some. Once I hit an area which somewhat has the velocity I am looking for, and shows some promise, I will drop back to working on the seating depth.

    Sometimes it all comes together, sometimes it's a bust. However, when I am done, the end result is generally as good as it gets, with that particular load or rifle. I do have to mention that I have only worked with basically straight factory rifles for the most part and only a couple of customs through the years. However, my process has been the same for all. I look for the best groups, at the velocity level I am trying to reach for a particular load, and the lowest ES and SD. Sometimes however, you don't always get what you want, but thats what keeps it fun.

    You on the right track, and based on your other target, obviously both the rifle as well as you, are definately capable of determining the end result.

    Good luck.
     
  10. dog caller

    dog caller Well-Known Member

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    Excellent points all the way around! I think my best course of action from here is to act on both of your suggestions. I will, of course, follow up on the load 2 group. The shooter in me wouldn't let me ignore 3 shots inside .311" (would anybody be able to?). I will also go back down to the 38g powder range and fiddle around a little. Maybe even run the test again, beginning at 37 and go up to 39 this time. After all, the reason I wanted to try this was to find that 2 percent wide band of consistancy. I live in East-Central NM and the temperature swings alone could cause major discrepencies in just a 24 hour period. If I find a Varget load, GREAT! If I don't, I should be able to live with what I have /ubbthreads/images/graemlins/smile.gif

    Thank you both for your input.

    DC