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Achieved my lowest SD ever

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  • TexMex247

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    I guess if you don't own a chronograph this probably doesn't mean much to you but I recently attained the lowest SD I have ever had in any gun I load for... and I have reloaded a dozen different calibers over the last decade.

    Last year, I finally bought myself a 308. Specifically a Howa 1500 with 20" heavy barrel. Not being able to leave well enough alone, I started reloading for it as soon as I had about 60 once fired cases in hand.

    As it happens the rifle likes both PPU's Match line and Federal's 168gr/175gr SMK GMM factory offerings. Naturally I bought some 168 SMK bullets and scoured the net for info. I wound up working with RL 15 and worked up a few loads.

    All of them(42-44gr) were MOA loads if I did my part behind the trigger but a node around 42.5gr seemed to be the sweet spot for me. I started exploring this range when I put down a .501" 5 shot group at 103 yards last month.

    I decided to do a primer test just to see if I could reduce my spreads a little within that area. The winner was a load of 42.4gr of RL15 using a Fed210 primer and PPU once fired brass that achieved an average of 2449 fps an ES of 4 and an SD of 1 !

    Now technically I think the SD is 1.7 and the sample size was only 5 shots but either way, I'll take it. I have put together many accurate and consistent loads over the years but this one takes the cake. I didn't sort bullets, cases, turn necks, use match primers, just found that magic powder bullet combo.

    Overall that group was just over an inch but I haven't settled on a COL just yet and luckily the howas box magazine will allow bullet length near 2.890" which will put me well into the lands with just about any bullet out there.

    For any of you long rifle types I'm sure you'll appreciate the relevant data. It may not mean much at 100 yards but at 600 yards a few fps makes a difference. Happy reloading gents !
    Target Sports
     

    robertc1024

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    That's mighty nice. I've never gotten below 4 or so. Bought some Lapua brass to try to help with that.
     

    dee

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    Your numbers may not stay that tight with rl15. It's not overly temp stable so as temp swings it may raise or lower as velocity will.

    Sent from my SM-G965U using Tapatalk
     

    orbitup

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    Nice. I got this the other day with my 308 and Peterson small primer brass.

    1ae926921967c044ce15c3b728e73ea3.jpg
     

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    TexMex247

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    As it happened, the 4 of 5 shots were exactly 2450fps. One somewhere in the middle was 2446.

    Strangely enough all shots being within 1 or 2 fps of each other (which is very good) usually does not produce the tightest groups.

    It's true this wasn't my best group of the day but on a couple of previous range trips I put down a few .5-.6" 5 shot groups. I never did chrono those rounds but they looked damn good on paper.
     

    avvidclif

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    I'm all ears too. As soon as I generate some cases I'm going to start working on loads for my Bergara. The guy that built it is a match shooter and he suggested starting with Varget (IIRC) 42-43 gr with the Sierra 168 gr Matchking. I'm going to use CCI BR2 primers, same as I use in the 6.5.

    Let the fun begin. I went out Tues and the guy 2 benches down was shooting the 2" steel plate at 500 yds and wearing it out. As I was leaving a guy showed up and started getting set up. He set up 4 wind flags. And the biggest tripod I've ever seen. The rifle was completely custom and he said at one point "Wildcatters forever" No telling what he had invested but it would have bought a real nice PU. My guess. I'm going to have to go out early in the AM more. There's some interesting folks show up.
     

    robertc1024

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    Dr. Ken Oehler told me once that any SD under 10 is probably a fluke, akin to a winning lottery number.
    I'd say he is a better chronograph maker than reloader then. I'd bet that a significant percentage of Orbitup's precision reloads have sub 10 SD's. I get them frequently too.
     

    LOCKHART

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    I have too, but they weren't necessarily the most accurate either. I have had loads that had high extreme spreads that would sometimes shoot clover leaf groups. Lots of variables when it comes to the reloading game. Almost nothing surprises me anymore after 54 years of doing hand loading. I bought my first chronograph from Dr. Oehler in 1973, and I've used it and later improved models from his company ever since. He is a remarkable fellow, and very knowledgeable. Just feel a thrill when you get a low SD, but don't read a whole lot into it.
     

    Deavis

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    Congrats and I dont want to take away from your excitement but 5 shots is simply not a statistically significant sample size. Anyone in industry analyzing statistical data will tell you the same thing, it means nothing except what you choose to assign it at that low level of sampling. Put 1000 shots across there and if you keep that SD, that's pretty great. Ken Oehlers SD statement becomes much more true at any really significant sample size.

    The group size is more impressive to me than the SD, good work.
     

    dee

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    Congrats and I dont want to take away from your excitement but 5 shots is simply not a statistically significant sample size. Anyone in industry analyzing statistical data will tell you the same thing, it means nothing except what you choose to assign it at that low level of sampling. Put 1000 shots across there and if you keep that SD, that's pretty great. Ken Oehlers SD statement becomes much more true at any really significant sample size.

    The group size is more impressive to me than the SD, good work.

    Quality components and equipment make it pretty easy imo.

    Sent from my SM-G965U using Tapatalk
     

    robertc1024

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    Quality components and equipment make it pretty easy imo.

    Sent from my SM-G965U using Tapatalk
    Yep. It really gets more important at longer ranges. At 100 yards - pfft. Being a jerk, I went to ballistics calculator. With a 6.5 Creedmoor, 20 fps equates to a 6" change at 1k. That might seem like all that much, but if you're in a competion...
     

    dee

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    Yep. It really gets more important at longer ranges. At 100 yards - pfft. Being a jerk, I went to ballistics calculator. With a 6.5 Creedmoor, 20 fps equates to a 6" change at 1k. That might seem like all that much, but if you're in a competion...
    With longer range consistency in all forms is key.

    Sent from my SM-G965U using Tapatalk
     
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