Efficient Load Development Process for Precision Field Shooting in 200 shots or less

Introduction

Here is the work-in-progress load development process crafted by Fred and Travis. We designed this process to balance efficiency and statistical significance. As a junior shooter, money is tight, and I’d much rather spend my time and money shooting matches, not paper. This process allows me to find an excellent performance quickly and easily. This process is not meant for Benchrest shooting or even F-Class. It is designed around field shooting disciplines like PRS, or NRL hunter. You can read more about field shooting here. Field shooters don’t have time to fine-tune out seating depth by the thousandth, or chase the lands. F-Class guys will often shoot their bullets within 20 thousandths of the lands, and tune them in tiny increments. While this may provide the best accuracy, it isn’t suitable for our kind of shooting. We may shoot 250 rounds in a match which can erode the lands as much as 10 thousandths. If our seating depth node was only 5 thousandths wide, we would be in for a rough day second day of shooting. We want to find a wide seating depth window so we can shoot the same load for the entirety of the barrel’s life. It is worth mentioning that we did all our testing at 100 yards, and still came up with a great load. While testing at 300 or even 600 years may be better, not everyone has access to a range like that consistency, and 100 yards is plenty to get the job done.

Group Sizes

For your load development to mean anything, you have to be able to be sure that your groups are not a result of chance. Although 5 shot groups are common, they don’t tell much about how the load performs. This can lead you to believe that your load is much better than it is, costing you points. Our research and testing found that a group should consist of at least 10 shots. Shooting 20 would be ideal, but with the cost of bullets, primers, and powder we tend to shoot 10. We performed tests to see if we could use 2 shot groups to eliminate poor groups and save shots. Some shooters like Clay Blackletter do this, but we found that it didn’t work for us.

Group Measurements

The two biggest issues with shooting for groups traditionally are the way they are measured, and the shooter bias. Shooter bias is a major factor when the shooter can see the group forming on the paper downrange. If the group looks bad, the shooter may rush and make it worse. If the group looks promising, the shooter may try hard to get those next few shots in the same hole. This skews the data and may make a good group look bad, and a decent group look amazing. Our load development process uses OnTarget to solve this problem. OnTarget is a software that takes individual shots and compiles them into a group. The software uses special targets with a bunch of bullseyes, one for each shot, which it then compiles and applies the proper scale. Using OnTarget, you cannot see the groups form as you are shooting them, which eliminates bias. The software has powerful tools that can be used to analyze the compiled group in many ways. We analyze our groups with a variety of numerical metrics like mean radius, SD radius the center-to-center group size, vertical SD, and horizontal SD. Numbers alone cannot give the complete picture, things like the group shape are also very important to consider.

Load Development Data Analysis

As we spoke about previously, we analyze our groups with Mean Radius, SD radius, group size, and X and Y SD. Many people like to analyze their groups with just the Mean Radius. The problem with this is, that although Mean radius is a very important metric, it means very little on its own. Mean Radius is the average distance from the center of the group, to each of the shots. Simply put, it is the average “miss distance.” Although Mean Radius is important, it means very little without the other metrics that we mentioned. X and Y SD aren’t extremely important to analyze the group, so we’ll leave them out for now. Groups with the same Mean Radius can look very different, so it’s important to factor in the SD radius and the overall group size. For example, the groups shown below all have a mean radius of 1, but they look drastically different.

Using SD Radius in conjunction with Mean Radius, we can understand more about the performance of the rifle, and the overall group size. The Mean radius alone is merely an average. The object of load development is to predict how the rifle will shoot. If this is based on just an average, it’s not significant. Standard deviation will tell us what kind of variation to expect in our groups down the line. The final touches in analyzing our group lie in the size and shape. The overall size works great to add to the data that the SD and Mean Radius show and the shape is important as well. It is important to recognize whether the group is round, stretched one way or another, or otherwise. This is what X and Y SD show numerically.

Load Development Data Processing and Organization

After you have shot all your groups, it’s time to compile them in OnTarget. It’s a good idea to save photos of the compiled groups to reference later. The data and pictures can be difficult to organize, so we’ve made a template to do so. The template also has a table which, when printed, keeps track of the brass’s firings, and what step it is in in the reloading process. When selecting a group consider all of the factors that we mentioned before. We do this by categorizing all of the metrics in 3 colors on the spreadsheet. Green is best, orange is ok, and red is bad. With the organization and analysis methods in mind, we can start loading.

Establishing Requirements

Group Size

Before any powder is thrown, or bullets are seated it is important to define what you need your rifle to do. For Competitive PRS shooting, MY requirement is a 1 MOA group or about one inch at 100 yards. We test this standard after we find our load. The test consists of three 10-shot groups and a combined 30-round group. We hope for the ten-shot groups to be under 0.75″, and the 30 rounds group to be under 1″. We have found that most of the time the ten and thirty round groups are similar. The shows lots of consistency in the load, and proves that it can perform. We also expect good velocity data. Over the 30-shot string, we hope the SD is at a maximum of 15, and ideally in single digits. This standard is only applicable to a high level of shooting. If you are just getting into the sport, I recommend that you don’t worry about your groups too much. Just get out and shoot a match. I have shot well in matches shooting a 308 with less-than-ideal groups and terrible velocity spreads.

Velocity

Knowing what velocity range you want to be in helps narrow down how many powder charges you need to test. Many shooters are no longer trying to push their velocities to the max for many reasons. Higher pressures make brass wear out faster and cause many other issues. Heavy bolt lift is a major problem that high pressures bring. It can make cause inconsistencies, and make working the bolt difficult during a match. In a 6 Dasher with a 107 SMK, I try to stay around 2800. I am comfortable going as hot as 2850, but no further. Many pro PRS shooters are stepping down to mild loads to avoid these issues.

Longevity

In my shooting, I have one goal. I want I be outside shooting matches, and not inside punching paper time and time again. This means that I do not want to have to continuously adjust and test my seating depth as my throat erodes. I want to find a wide window where I can set it and forget it for the entirety of my barrel’s life

Components

Bullet

The first obvious step is picking a bullet. We like to pick our bullets based on the weight, BC (ballistic coefficient), and track record. For example, I knew that the Sierra 110 SMK and the 107 SMK were in a good weight class for my cartridge. The 110 SMK would have been a great bullet, but because they’re impossible to find, we picked the 107. Both the 107 and 110 have great BCs, and people say great things about them so we couldn’t go wrong.

Powder

Once you have chosen your bullet, it’s time to pick a powder. We look for temperature-insensitive powders, and ones used often with our cartridge. Depending on your seating depth limitations from magazine length or otherwise, you may have to factor in case fill of the powder. For example, some stick powders fill up a case before an adequate velocity is reached. This may require you to look at ball powders, which may work well, but are generally less temperature-stable. Varget is a very popular powder for the BR family of cartridges, so that was what I chose. Varget is known to be pretty temperature stable, so there should be minimal velocity change at different temperatures. This is very important when you are shooting matches, especially in the spring. It can be 40 degrees when you zero your rifle and gather velocity data, but get up to 80 degrees at noon.

Brass

Brass is also an important factor. I’ve shot my Dasher in both Lapua and Alpha Brass, which are both considered to be the best available. Good brass has constant volume which translates to lower SDs and less vertical dispersion at range. I also segregate my brass by firings to keep everything consistent. This also helps you avoid running into problems like case head separations at important matches.

Seating Depth

We found that starting with a solid seating depth works best, and it allows you to see what actual results you will get out of your powder charge. Our seating depth tests stemmed from Short Action Customs’ research on bullet jump. This research suggests that the seating depth is dependent on the bullet, not the rifle. This means that Fred and I can jump our Sierra 107s the same in different rifles. This also means that I will not have to adjust my seating depth when I switch barrels. If you have already found what jump your bullet likes, you can skip the seating depth test. The research shows that 40 thousandths off of the lands seems to be a good starting point. You can find the lands in your barrel using the fingernail technique. Ballisticians at Berger Bullets say that each seating depth should be 0.040″ apart. With that in mind, if you find two consecutive seating depths that shoot well, then you are golden. That gives you enough room to not have to worry about your seating depth for a while. We test either 10 seating depths or how many your bullet and powder combination allows. Sometimes you will run out of bearing surface on your bullet, or start to compress powder before you get all 10 depths, which is no big deal. If the powder is compressed, the bullet will be harder to seat, and the powder will not shake inside the round. If you run out of the bearing surface, you will be able to see a gap between the neck and the bullet. In summary, to find your seating depth, start 40 thousandths off of the lands, and work your way back in 40 thousandths increments

Powder Load Development

Once you have decided on your seating depth, it’s time to test your charge weights with that chosen depth. Testing charge weight is similar to testing seating depth. Often, we will start with the maximum velocity we are comfortable shooting, and work our way down in 0.2-grain increments. Sometimes, if we want a larger window of testing will will shoot 10 shot groups, and test 10 different charges. To estimate our velocities, we use Gordon’s Reloading Tool. When estimating, make sure that the H2O volume value is correct in the software. Variations in brass across manufacturers and lots can cause errors in the pressure estimation. Even though we shoot lower pressure loads, we still shoot from lowest to highest charge and check for pressure signs. Our spreadsheet will automatically give you 10 charges based on the maximum charge that you input.

Shooting for Load Development

While shooting your groups, it is vital to record velocity data for all of the shots. Velocity SD and ES are very important to your groups’ overall performance, and they help get an idea of your load as a whole. Also, make sure to stay hydrated while shooting so you can ensure that the groups reflect what the rifle is doing, not how good you are feeling. Take breaks, both for yourself and for the integrity of the chamber. Shooting too fast wears out the barrel faster, and may cause pressure issues. To track the temperature of your chamber, check out our barrel temperature gauge.

Cliff notes

Below is the basic process to refer back to

1. Seating Depth
   1. 10 round groups
   2. .040” increments
   3. Start 0.040” off lands
   4. Seating depth is bullet specific, not tailored to each rifle
   5. Record velocity SD for each seating depth
   6. 1 shot per bull to reduce shooter bias
   7. Use OnTarget TDS to compile group
   8. Analyze Mean Radius, SD Radius, group size Vertical SD and Horizontal SD
2. Charge Weight
   1. 10 shot groups
   2. 0.2 grain increments
   3. Use GRT or QL to find a max charge (make sure to input case volume H2O)
   4. Record velocity average, and SD
   5. 1 shot per bull
   6. Use OnTarget TDS to compile group
   7. Analyze Mean Radius, SD Radius, group size Vertical SD and Horizontal SD
3. Confirmatory Test
   1. Three 10 shot groups and one 30 round group
   2. Record velocity data
   3. each 10 shot group must be under an inch, ideally under 3/4 or 1/2
   4. SD must be under 15, ideally under 10