Reloaders Corner: Accuracy 2

Accuracy matters! Now here’s what matters to accuracy… This article discusses 5 essential steps that pay off big.

Glen Zediker

Last time I wrote a little “essay” on the importance of accuracy and a few ideas on why it matters and how to judge it. That’s all well and good, but the part I knowingly left out was to say more about “how” to get the most of it. Here’s a few points that, over a many-many years, have proven themselves to me to improve the quality of on-target perforations, and, to make sure I’m clear, that is manifested by smaller-diameter shot groups. There are a plenty of others who agree with these tips. There are plenty of others who might not agree with all of it, and even a few more who would love to add their own “can’t miss” components to this mix. But here are mine.


ONE: After-the-fact concentricity. By that I mean actually checking loaded rounds on a runout indicator. Concentricity is pretty much the goal for sizing, seating, and neck-related case-prep steps, like outside case neck turning. However! All those things are done to help support concentricity, but not a one of them is concentricity.

Concentricty is the centered relationship of all influential circles in a cartridge case, with the reason that a more concentric round will have its bullet looking down dead center into the rifle bore: ultimately, if the loaded round spins “flat-line” it will shoot better than those that don’t.

It starts with brass selection and then likely also segregation. Then it moves on to the quality of tool alignment.

I have checked enough factory-loaded rounds though a concentricity fixture, and those that show the best group the best; even if the overall group from random selections is so-so, “flatliners” shoot smaller.

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TWO: Inside flash hole deburring. I know I’ve mentioned this before, but this simple and easy step shows up on target next firing on thusly-prepped cases. It improves propellant ignition consistency and, depending on the tool used, also ignition efficiency.

Inside deburring tool
How and why an inside flash hole deburring tool works is pretty clear to see. Despite the fears I’ve heard, it will not hurt the integrity of the case.

There’s a burr inside most cases that resulted from manufacture (with only a few drill-cut exceptions, like Lapua, cartridge case manufacturers punch the flash hole). This burr is variable in size and scope, but it acts as a block to the spread of primer flash, and it’s redirecting or misdirecting the flash at the same time.

It only has to be done once. Ever.

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THREE: Primer pocket uniforming. This helps because it lets you set each primer the same, and also fully. The reason is that it squares the “edges” or corners of what otherwise is a slightly bowl-shaped cylinder. A perfectly seated primer is sitting square and flush on the bottom of the pocket, with its anvil legs compressed. This “loads” the compound for rapid and consistent ignition. If the primer isn’t seated fully then the firing pin finishes that job before detonation. That creates what equate to time variables — inefficiency.

Funny, but clean primer pockets don’t shoot any better than dirty pockets. What matters is flat pockets.

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FOUR: Consistent case sizing. There is a widespread fear, especially among some “accuracy” fanatics, about sizing ops. There’s also a lot misunderstood about full-length sizing versus neck-only sizing and so on. But. What matters is that, whichever tooling and how much sizing the cases are treated to, it needs to produce dead-same cases. Consistent case expansion dynamics is not often talked about, but it’s influential, especially on longer-range rounds. Just in general, going a little on the “light” side with sizing might seem like a good idea (less stress, less working the metal, etc.) but it can also lead to round-to-round inconsistencies. My belief is that it’s better to be more “positive” in sizing ops, and by that I mean to reduce a case neck 0.003 inches rather than 0.001 prior to seating a bullet. Get all the case shoulders the same height. Running extra-light case neck tension and leaving case shoulders where they emerged last firing may not reproduce round-to-round consistency, unless the rifle chamber was perfect and the cases were too. A little more sizing works the best for the most of us in the most rifles.

Forster seating die

FIVE: Invest in a good seating die. No doubt: the bullet seating operation is the “last thing” that happens and it’s also the one thing that can corrupt the care and treatment given to the quality of the loaded round prior. A sleeve-style seater, well machined, goes a whopping long ways toward preserving alignment, and, therefore, concentricity. Also make sure that the stem in yours comes to rest well down onto the bullet ogive, and, above all else, is not contacting the bullet tip! That will wreck a round.

seating stem
Remove the seating stem and drop a bullet into it. The farther down the ogive or nosecone the step recess grips the bullet, the better. If it’s only pressing down against the bullet tip, a crooked seat is assured, along with inconsistent seating depth.

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This article is adapted from Glen’s newest book, Top-Grade Ammo, available at Midsouth HERE. For more information on that and other books by Glen, visit

11 thoughts on “Reloaders Corner: Accuracy 2”

  1. What flash hole tool is shown in the photo with cut out brass? I like that it has a built in stop rather. I went to Midsouth’s website but couldn’t find anything that resembled the one in the photo.

  2. These are great tips; thanks for putting them up. One thing I’ve always wanted to see published with these kinds of articles is a proper statistical analysis of such steps/processes. It’s terrific to have ‘confidence’ in tools, procedures, and so on, but to me it’s far more valuable to have enough data and proper analysis to be able to quantify the benefit of each. I’ve done some of this myself, and it can be very enlightening just how different the perception can be from the reality sometimes.

    1. My guess is you’re reloading for quantity not accuracy on a progressive press. Sub m.o.a. requires the detail you get only with a single stage press.

  3. Glenn,do you have any ” pointers” on how to handload bottleneck cases, such as the .357 SIG cartridge? The seating and crimp are my obstacles, and the “crushing” of the shoulders. I resize 40 S&W cases( a “No-No” per some Handloading folks as the cases are just a little short to hold the bullet). But I find that they actual load and “lock” fully, while some of my stock manufactured .357sig cases that are prepped and loaded do not lock in , which I notice has a slight bulge at the beginning of the shoulder. I have checked the 40 cal. cases for any signs of high pressure or head separation, damage to shoulder or mouth. There is none. And after firing these 40 cases, they do “grow” slightly to make up for their shortness, right? The real reason I repurpose the 40 S&W cases is the .357 Sig cases are expensive to purchase, and there are a huge amount of 40 cal cases everywhere at the local ranges free for the taking. Any info and advice will be greatly appreciated. I really don’t want to have to purchase a 40 or 45 or a 9 mm, just to be able to further my love of both shooting and Handloading. Thanks for any replies from anyone else too!

    1. I freely admit when I don’t know, and I don’t know anything about the .357 Sig. I wish I could help from some voice of experience, and maybe one will arise from this forum…

  4. Thanks for the article. Reminded of some things I have stopped doing to speed up the loading process. I will return now after reading this article because you are spot on with the reasons for each step mentioned. I am fanatical about shot grouping; don’t know why I would sacrifice accuracy for speed in reloading. Accuracy is the most logical reason for reloading — after all.
    Thanks again.

  5. Glen,
    I’ve, for years, been trimming my rifle cases with a manual RCBS trimmer assuming that my cases would all be the same length. I length checked a batch of 50–300 Wby Magnum cases after I had trimmed them and have 16 different lengths! I’m using a Stoney Point Case Gauge. What can/should I do to remedy this? Any ideas will be appreciated. Great article, I just ordered 3 primer de-burring tools.

  6. Well, and I hate to say this, but a different trimmer would likely help. Any of the collet-style mechanisms are going to allow some inconsistency. I strongly recommend LE Wilson. That will, not may, end your issues.

  7. Thanks Glen,

    I could have bought 10 LE Wilson trimmers vs the time and rounds produced that didn’t meet expectations!

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