How to Find Your Absolute Best Load

Written by Sierra Bullets Ballistic Technician Rich Machholz

Nearly every day and for sure every week each of us technicians get asked how we work up our own personal loads.  Now I don’t live in a fantasy world so I think it is safe to say we all use a somewhat different method to achieve the same perceived result.  So my method is outlined below.  But I have to warn you, I have been known to throw a load together only to find that it is good enough as is without further testing.

Case in point – I got a new-to-me IBS Heavy Gun and since it was new-to-me, I borrowed some off the shelf RCBS dies from my brother in-law.  The gun came with some Norma brass luckily because it is a caliber I would not have picked on my own.  Since it is a 300 Magnum I wanted to shoot our 210 grain HPBT MatchKing bullet #9240.  I have a good supply of Retumbo on hand so I dreamt up a load and threw it in the first 20 cases I could grab that had been primed with W-W WLRM primers.

That chore completed, I mounted a Burris XTR 8-40X to the integral 20 MOA rail and headed to the farm where I have a 250 yard range.  After I got all the benchrest paraphernalia set up I positioned myself so I could look through the bore of the rifle and proceeded to bore sight it.  The first shot was on paper low and slightly left so I clicked to the hole and fired five more shots.

1st-group-6So far that has been the extent of my load development for that rifle and I think you can see why.

I had another such stroke of good fortune with my primary hunting rifle a Ruger M77R 7×57.  For years I had shot IMR4350 and the Sierra 140 gr SPT ProHunter #1910 but a Montana Mule deer hunt brought with it the prospect of longer than normal shots so a search began for a flatter load.  I chose the streamlined Sierra 140 gr SBT GameKing #1730 for a bullet and VihtaVuori N165 for the powder.   I had some new W-W 7×57 Mauser brass and plenty of WLRs so I checked the manuals, picked a load and assembled three shots.  I used the same COAL as my original ProHunter load.  Over the years that load has produced many 1/2 inch 3 shot groups, just like it did originally.  They don’t all work like that but it is nice to be lucky.

So, when I’m not being lucky how do I really find my loads?

I do have a method besides being lucky and it is as follows:

First things first, select a bullet and a powder. Find the powder charge that works for that bullet. This is easily done with a “Ladder Test”.  You may need to shoot several tests to find the load that suits you.

Next, swap whatever available and appropriate primers you have through the above powder charge to establish a balanced ignition.

Shoot this test in one trip to the range as you want everything to be as similar as possible.  This is best done on the same day and same target so you can get a quick visual comparison of group size and POI.

Then, using that powder charge and primer as established previously, start working the bullet seating depth from magazine length back at least .030″ to .045″ less than max mag length in increments no greater than .010″ to establish the best COAL for this combination.

After firing your tests in .010″ increments there will be a true standout dimension.  To narrow that down even closer, load groups at your previously determined dimension AND .005″ greater AND .005″ less than the previous best dimension to determine the true performance corridor.

The result of all this testing is a stable, well-balanced load that will be consistent day in and day out tailored specifically to your firearm.

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22 Responses to How to Find Your Absolute Best Load

  1. Pingback: Sierra | How to Find Your Absolute Best Load |

  2. firstriverbend says:

    Good general description of finding a load, thanks!
    Don’t you just love it when a first loading is great!
    When I first started shooting IPSC, found a revolver load on first try that always shot 1 5/8 inch at 25 yards out of a 4 inch barreled Service Six. Like you, could never see a reason to look any further for that revolver. 🙂

    Like

  3. Randy Hillyer says:

    The problem, and I do it too, is try not to be as the tv commercial indicates, a settlor. I always think what if! I had a .270 load shooting 1 1/2 inch groups at 100 in two guns. Should have shot closer to 1/2 inch groups. Played and played with the powder and final looked up in my gun room and saw a different kind of primmer. Tried the new primmer then reduced the group to right at 1/2 inch. The other thing I have always done is use 5 shot groups, never 3. Lot less luck involved in 5 shot groups. This made the same difference with the 130 grain bullet, as well as the `150 grain bullet.

    Liked by 1 person

    • firstriverbend says:

      Agreed, but then if one is shooting a long range where 1/2 inch is going to make a difference versus 1 1/2 at 100, then it does make sense to chase the group.
      However, if one only is going to have opportunities at 50 to 100 yards, chasing a smaller group means busy work, as game will not be able to tell the difference.

      It is all about realizing when good enough is really “good enough”. 🙂
      Too much is written about wringing the last little bit out of a group/rifle/handgun when it is not needed. More often the time spent chasing group size is better spent on shooting practice and learning what influences the shot in the field.

      An example would be one IPSC match long ago, one stage was at 75 yards. Most were dismayed and just launched rounds down range hoping for a hit on target. This was being done by “better” shooters than myself and with much more expensive firearms, capable of incredible accuracy.
      The problem was one of attitude, not group size.
      I was not concerned about the range, as I had spent a fair amount of time learning what my 1 5/8 inch (at 25 yards) .357 magnum groups would do and how to make it work well. I had high score on the stage, with one of the least accurate firearms of the match.
      This was because of practice and understanding what everything was doing in and out of the gun as I shot. Shot that stage more as a NRA High Power stage/target and had mostly 5 hits.
      It is more about finding what is needed for the usage, than the tiniest group that can be shot, not always, but often. 🙂

      Like

    • Rich says:

      Thanks for your comment Randy.
      I used to shot 5 shots for every test but as time passed and components got more scarce and expensive I found valid initial load testing could be done using 3 shot groups. While it is hard to swallow, it is a fact that if the firearm won’t group three shots, it probably won’t group five either. In most cases a 5 shot group is more a test of the shooter and firearm and not so much the load. And … In a hunting gun your first shot is almost always the best shot so if you fail on the first shot chances of the following shots being effective aren’t all that good.
      My competition guns do get the 5 shot treatment however but they are custom built and bedded differently than my factory hunting rifles and they do get warm up shots in the form of sighters.

      Liked by 1 person

      • Dave says:

        I agree with you Rich. I usually load three rounds with different powder, primer combination and take it from there. Clean barrel for the first group and clean barrel for the rest of the groups as well. I take it from there to fine tune any loads that showed promise. I’ve found that velocity is the most important factor. If for example I measure a velocity of 2700 fps with a certain bullet, powder, primer load I’ve found that the same bullet will shoot just as well with another powder, bullet, primer that has the same velocity or very close the same velocity. I think this has to do with barrel harmonics, much like a Browning Boss system works.
        Thanks for the article.

        Liked by 1 person

      • Gary says:

        Right, I have seen the same thing. I’ve been shooting for 48 years and reloading for 33 years. In my heavy barrel rifles 5 shots is fine, but in the light weight sporter barrels on my hunting rifles, well there is just not enough time to let the barrel cool. I can get three shots, let the gun cool while shooting another gun or doing something else. Five shots would have the barrel so hot I would start seeing group issues just from that. Very well said.

        Liked by 1 person

  4. Rich says:

    I’m glad you enjoyed the article and thanks for your comments.

    Liked by 1 person

  5. I appreciated the short, but clear, road to a very good load for YOUR gun.
    I will hang it in my shack — it is better written than the one I have and work by today 🙂

    May I copy the text (with link to Your original) and place it on my site ?
    ….and if yes : Post it, and also transfer it to Norwegian ?
    The site has been “down” (with me) for some years, and I am presently removing rust. 🙂

    C-F

    Liked by 1 person

  6. Rich says:

    Be my guest Carl-Frederik, I’m glad I could provide some assistance.

    Liked by 1 person

  7. Darrell Holland says:

    Gentlemen,

    Note that COAL is not really what we are looking for, it is Base/boltface to Ogive that we are concerned with. COAL will vary often times more than .005-.010 in a box of bullets (meplate uniformity, lot # of bullets, etc) when compared to base to ogive dimensions. This can cause those flyers we experience because the exit timing has changed.

    Great article Rich, thanks for sharing. Wanna sell that 300 Mag???

    Respectfully,

    Darrell Holland

    Liked by 1 person

    • Rich says:

      At this point of load development COAL is still paramount because we need function. Remember, this is primarily a hunting application and a hunting load is useless if it is not magazine friendly and we’ll let the seater die do the sorting for this phase. After we get the COAL determined then is the time to start matching rounds using ogive to base measurements with Darrells excellent tool or other similar tools and that is subject material for a whole new article.
      Thanks for the comment Darrell and everything has a price but that 300 won’t be cheap!.
      Rich

      Like

  8. Mr. Camek Lothar says:

    It is exactly how I find my loads step by step. To define the brass length overall seating the bullet I take a prepared brass case and do it with the bullet in the gun to get the exact length without free flight way of bullet. Then I do it your way to seat o.o1 up to satisfying results.

    Like

  9. Glen Lambert says:

    I want to tell you how much your work developing loads is appreciated by me and others like me who depend on your work. I am retired and reload as a hobby and don’t have the resources to try all the different powders, primers, seating depths, etc to find the best load. I do tweak your loads to match my individual guns.
    Thank you for your work.

    Liked by 1 person

  10. bill scott BA Okla. says:

    I have used the method that you have and it works well for me as well. When I am working loads for a thin barreled hunting gun I keep a small ice chest with cold water in that I can take awash rag and dip it in it and wipe it down to cool it. It shortens the time for the barrel to cool for your next set of shots. I have been loading and shooting since I was 14 and l am 75 and shoot at least three to for times a week. Great to be retired. Old man from Oklahoma keep up the good work.

    Like

  11. Dan says:

    Thank You for your writeup. I found it very helpful. What increments do you use for your powder charges for a rifle? Several friends of mine use 0.5gr increments, and one friend uses 0.3gr. The friend using 0.3gr increments does so to avoid missing an accuracy sweet-spot, claiming 0.5gr is too wide.

    When you mention “swapping primers to obtain a balanced ignition”, what does this mean? How do you confirm ignition is balanced?
    Thanks!

    Liked by 1 person

  12. Rich says:

    Hi Dan, when I am working up loads I use 1% of the total case capacity of that case with the powder I have chosen as my incremental increases. So a 6.5 Creedmoor holds about 45 grains of 4350. My increment of adjustment will be 1% of that or 4/10ths of a grain (.4). A 223 will use 3/10ths and a 270, 280 or 30-06 will use 6/10ths or a 300 Win Mag will be 8/10ths. Naturally you can round up or down but the idea is to get good uniform increases without by passing your accuracy or performance corridor.

    Your chronograph will tell you when you have a good balanced load. When the extreme velocity spreads are consistently low and your accuracy consistently good you can consider your load development successful. Primers can play a very large part in this phase of load development.
    Rich

    Liked by 1 person

  13. Virg says:

    For a new reloader what is a “Ladder Test”?

    Like

  14. Rich says:

    A ladder test is based upon a series of incremental charges fired at a single aiming point.
    In practice you select a powder, next you load incremental charges based upon 1% of the case capacity of the cartridge you are loading, one shot per increment. These are fired at a target no closer than 200 yards. The target has a single aiming point in the middle of the paper. All shots are fired at that single aiming point on that target. As a shot is fired down range it is mapped on a duplicate target at the bench so you know where each shot lands on the down range target. What you are looking for is two or more increments that shot together or clump up indicating a favorable node in your barrel.
    And that is a ladder test as I use it.
    Rich

    Like

  15. Torben says:

    Hello Rich, i’m going to try your way to find the best load. I have a question though…..i’m not sure i understand why you are using max. magasine length as an index/reference ? Is it because you can make coal so long it will not fit in the magasine but you are still not at mcoal for your rifle or is it just your way of doing it ? If magasine length isn’t a problem wouldn’t you use mcoal as reference ?
    Thanks
    Torben Gadegaard

    Like

  16. Rich says:

    Yes Torben, it is absolutely possible to load ammo too long for the magazine.
    Rich

    Liked by 1 person

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