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More Chrono data

Discussion in 'Reloading' started by n2extrm, Apr 18, 2010.

  1. n2extrm


    Feb 24, 2009
    As some of you may remember I posted some chrono data back in December and some problems I may have had.

    I finally got back to the range today and made some adjustments to the load trying to get SD, ES and velocity where I wanted it. I tried increasing neck tension and varying the charge to see where I would head.

    The book data is for .308 winchester, 168g sierra match kings bthp, large rifle primer, 42.0g re15, seated to 2.800 inches should yield 2600 fps.

    My loads and data is as follows. I have included high low es sd and velocity to keep it simple.

    1st string 7 shots. Federal brass full length sized, 168 SMK, fed 210m primer, 42.0 grains RE15, seated @ 2.800"
    High 2502
    Low 2441
    ES 61
    SD 20

    2nd 10 shots. Hornady Match Brass, neck sized with .335 bushing, 168 SMK, fed 210m primer, 42.1 grains RE15, seated 2.800
    High 2468
    Low 2316
    ES 152
    SD 41.7

    3rd 10 shots. Hornady match Brass, neck sized with .335 bushing, 168 SMK, fed 210m primer, 42.4 grains RE15, seated 2.945"
    High 2466
    Low 2372
    ES 94
    SD 28.3

    4th 10 shots. Hornady Match Brass, neck sized with .331 bushing ( better neck tension) 168 SMK, fed 210m primer, 42.6 grains RE15, seated 2.945"
    High 2475
    Low 2414
    ES 61
    SD 22.6

    The groups are close in size, but the best group at 100 was probably #1 then # 3 by #4 I think I was spent and it was useless to measure it. I was also more worried about hitting the chronograph then perfect shooting!:rofl:

    My thought is to leave the smaller bushing and longer length, bump the charge up to 43.0, 43.2 and 43.4 and see what numbers are revealed. 43.6 is max published, but I am bellow velocity and I am longer then published length so I think I will be safe even a little above the max published.

    Suggestions or thoughts?
    Last edited: Apr 18, 2010
  2. dougader


    Apr 17, 2004
    If you're shooting for both group size and velocity at the same time I don't think you'll get your best groups because you're thinking tooo much about blasting your chronograph. Shoot for velocity first, then shoot the same load for group size.

  3. srd


    Apr 4, 2009
    I load 11 rounds of each test round. I mark the holders as to what is in each along with each target before i leave fror the range. Shoot for group size first and then chrono the last round after all the loads have been shot. . I have learned over the years that you can have a lousy SD and accuracy can be excellent.
  4. n2extrm


    Feb 24, 2009
    Yeah I see that can be a problem. I actualy thought of just buying the spare screens now. :rofl:Groups have been good till I get past 200 yards. That is why I started to play with the chronograph.

    Trying this actualy. I know what seemed to group better and worse, then was looking at the chrono data. Just trying to get the most out of the load.

    Thanks guys, I have been reading and re-reading and I think the Hornady cases may be an issue. It seems they have a larger capacity then most, I think that may be the slower numbers and higher ES and SD. I plan to go up a little and see where it heads. No pressure signs on the brass and primers, easy bolt lift, so I will bump it up and see where it goes.

    :wavey: Thanks again.
  5. GLShooter


    Jan 3, 2006
    Phoenix, AZ
    I like to load to at least 90% on my rifle cases. It seems to help for consistency. The closer to 100% density the better for me.

    I always shoot for group as I chrono my ammo. I use a Millennium CED Chrono and have not hit any screens yet. 10 feet from muzzle to screen. The big area is plenty big enough to steer around.

  6. WiskyT

    WiskyT Malcontent

    Jun 12, 2002
    North Carolina
    Your accuracy beyond 200 yards is probably off due to paralax. That is an issue that is a thread in and of itself. The short version is, if you don't have a scope with paralax adjustments, and you don't make 100% certain that your eye is totally centered in the lense, you can move your point of impact easily as much as a foot on each shot. That is the trouble I was having with my regular bubba deer hunting scope. A guy showed me a trick and it fixed it right up, but it's not the right way to do it. It's just a field expedient that works. You have to move your eye forward or backward until you have a very small area to sight through. That small area will be in the center of the scope. To see what I'm talking about, rest your rifle on bags so it will stay still without you touching it and it is sighted on a 300 yard target. Move your head left and right and see how the reticle moves the opposite way.

    If your gun/load shoot a good group at 100 yards, it will shoot a good group at 300, you just have to find a way to make it work. The bubba scopes are set to be paralx free at 100 yards, they have a lot of error at 300 and beyond.
    Last edited: Apr 21, 2010
  7. n2extrm


    Feb 24, 2009
    Thanks Wiskey. Almost all of my scopes have paralex adjustment only one does not a 3-9X for the woods. I just seem to get looser and alot more drop then I would like at the longer rangers. It could be 100% THE IDIOT AT THE TRIGGER. I am just trying to learn and enjoy while getting the most out of it. What do you think of the velocity I am getting out of a 26" barrel remington 700?
  8. WiskyT

    WiskyT Malcontent

    Jun 12, 2002
    North Carolina
    Regarding paralax, I see that you have that covered.

    Regarding velocity, the numbers look a bit slow. My older Hornady manual doesn't have data for R15, but with a 22" tube and numerous powders with their 168BTHP, they get higher velocities, 2600-2700. I'm not saying boost the R15 charge, because I don't know what the max is, but you might be better off with a different powder. You should be able to get more along the lines of 2800-2900 with a 26" bbl.