Reloading for Precision Rifle: Building a Baseline

Ask 10 different shooters for reloading advice and you are likely to get 10 different answers. Everyone has their own maze of steps and rituals in the pursuit of shooting small groups. From complex brass preparations to “magic” seating depth values to expensive equipment, reloading seems more like alchemy than a simple science experiment. The reason there can be so many different answers is the fact that reloaders are tackling many different problems at once and don’t even know it. With a little clarity, I’ll help shooters new to reloading focus on the things that matter most to keep the process simple and ammo shooting precisely.

The article assumes that you have a precision bolt action rifle that is capable of shooting 1 MOA or better with factory match ammunition, are using quality reloading components, have learned the reloading basics, and are capable of shooting good groups consistently.

Tuning

The purpose of reloading for precision rifle is to consistently shoot small groups. To achieve this, the ammunition used should produce consistent velocities, illustrated by low extreme spread (ES) and standard deviation (Sd) values. You should first establish a solid foundation by experimenting with two principal factors that can affect velocity: powder charge weight and bullet seating depth. You’ll know you’ve hit the sweet spot of the rifle where the groups get noticeably rounder, more consistent, and smaller. In general, experimenting with the powder charge and bullet seating depth is called tuning. There are more tuning methods, but they depend on establishing this base first, or you will have no idea if they really work.

Case Prep

Case prep can be simple or complex. What you’ll find is that you can get great results with new cases, that is case that haven’t been sized to your specific chamber. What makes quality brass shoot well is its consistent dimensions from case to case. If all you do is make each case consistent you’ve accomplished much of the task. Follow the basic steps on brass prep and measure often.

On new brass, shipping may have caused the mouth to deform, so you may need to run a mandrel through the mouth to round it out. If you find the inside edge of the mouth shaves a little copper off the jacket, chamfer the mouths. Other than these two issues, good quality new brass can be loaded straight out of the box.

If you are using fired brass, clean it by wet or dry tumbling so you don’t transfer grime to your reloading dies. Don’t bug out which method is better; precision isn’t dependent on whether the inside of the case is sparkling new or has carbon residue. My dry tumbled brass shoots identical to new brass. Instead, pick a cleaning method and perform it consistently.

Powder Charge Weight Start

The first component we begin experimenting with is powder. This will get us on or close to the rifle’s sweet spot. After this, we refine it with bullet seating depth.

Here we will load up 10 separate powder charge weights in increments of .03 grains and then shoot them over a chronograph. To set this up, use your preferred reloading guide to look up the maximum powder charge for your powder and ammo combination, then subtract 1.0 grains from that number. For example, if the maximum charge is 41.3 use 40.3 grains as your maximum load.  With the new maximum load number subtract .3 grains from each new sum and keep going until you have 10 loads (40.3, 40.0, 39.7, etc.). Note: Some people subtract .2 grains, but I favor .3 grains because it gives me 1.0 grain wider window to find the sweet spot.

The reason you don’t want to use the reloading book’s maximum charge weight is that once the barrel gets seasoned after about 100-200 rounds, your ammo’s velocity will likely increase by 60 to 80 feet-per-second (fps) and may exceed the maximum pressure rating.

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My recommendation for how many cartridges to load is as follows: Load six cases of your lowest powder charge, then load three cases each with the incrementally increased charges. That will give you three cartridges of the lowest powder weight to zero the rifle with, and then three of each weight for shooting groups. You will have a total of 33 cases with powder.

To keep track of cases, I put stripes on the cases with a colored Sharpie. I make a note on an index card which charge weight is which color and the quantity of markings and keep it with the ammo.

Bullet Seating Depth Start

Once we have the powder loaded, we will seat all the bullets to the same seating depth. It’s only after we test the powder charge that we begin to experiment with bullet seating depth.

A safe bet is to set the bullet depth .020 inch back from where the bullet touches the rifling, also referred to as the lands. Jamming it into the rifling may create unsafe high pressures or cause the bullet to stick and create a mess if an unfired cartridge is extracted. The .020 inch is an arbitrary starting point that shouldn’t cause pressure issues. In reloading circles, you will hear people swear that a specific seating depth number produces small groups. Ignore them, it infers that every rifle has the same sweet spot irrespective of cartridge velocity, barrel length or barrel profile. It’s an extraordinary claim that doesn’t jibe with the physics of shooting or experience.

Testing Powder Charge Weight

With a fresh batch of ammo complete, it is time to hit the range for testing. The powder charge weight test will get us on or close to the sweet spot.

You will need a chronograph to measure velocity. Use a quality chronograph like a MagnetoSpeed V3 Ballistic Chronograph ($449) or the LabRadar ($625). There are more affordable options out there that can work, but experience has proven they are more susceptible to faulty readings, may require precise placement and can exhibit finicky shooting zones.

For targets, use a sheet of paper or carboard backer with the same amount of targets as load increments, in this case 10. The smaller the aiming point, the better, but remember you still need to be able to see the targets at distance. I like to use 1-inch round stickers as targets.

When you are ready to test your loads, there are two predominant methods to follow. If you are looking for precision across a wide range of distances, I recommend using the Saterlee method. If you are shooting a specific distance like 600 or 1,000 yards, use the Optimal Charge Weight procedure. Both tests are shot at 100 yards. Sometimes these two methods point to the same charge weight.

With the Saterlee method, shoot each increment starting from a low to high charge weight and document their average velocity, ES, and Sd values. Stop the test if you experience heavy bolt lift, it’s a sign of high pressure.

Once you have the average velocities written down for each increment, look for adjacent velocities that are very close and appear to create a flat spot (velocity node) in the graph. There are usually three groups close in velocity, sometimes only two. By close, I mean within 2-10 fps of each other. The other groups will show roughly 15-25 fps, or more, between them. Choose the powder charge weight that sits in the middle. If you have two flat spots, choose the lower charge weight. The ES value should be between 7 and 20 fps with an Sd around 4 to 10. With new barrels, I stay away from flat spots near the maximum end because velocities may climb once a barrel is seasoned.

Mark the targets charge weights and velocities and keep them to use for data on future tests. Group size isn’t important here, velocity is. You’ll fine tune the group size with bullet seating depth test.

There’s a chance that there is no flat spot. This even happens to experienced reloaders. In such a case, I choose the load with the lowest ES and Sd values.

For shooting specific distances, Optimal Charge Weight can get you really small groups, despite relatively high ES measurements. For this method, accuracy and precision are important — take your time to shoot good groups, one charge weight per target. Instead of looking for similar velocities, you are looking for similar points of impact. I take tracing paper and mark the center of the target, then overlay that on each target and mark the center of each group. Of the two or more that overlay, choose the charge weight in the middle. For example, if 39.7, 40.0, and 40.3 had the same point of impact, choose 40.0.

Bullet Seating Depth Test

After you find the powder charge weight, it’s common to experiment with different bullet seating depths. Adjusting the bullet seating depth affects the bullet’s timing to the sweet spot. Create a bullet seating depth list. The first number should be your original bullet seating depth, now subtract .005 and continue that until you have at least 10 different seating depths. For example, if your original seating depth was 2.195, your next should be 2.190, then 2.185, then 2.180, etc. Load three cartridges for each depth. You’ll know when you are close to the sweet spot when your groups are round or triangular and cluster together. Horizontal or vertical strings show you are out of time with the sweet spot.

Final Test

Load 15 rounds of the winning powder and bullet seating depth test and shoot five, three-shot groups. Average out the group size to give you an idea of the dispersion of the load. Some groups will be very small and some may be just OK. If your groups are mostly roundish, you are good to go. If they are stringing vertically or horizontally, explore adjacent load charges and bullet seating depths. It’s not uncommon to go back and refine the load.

Brass Prep & Results

I shoot PRS-style matches and paper targets to 1,000 yards, so my expectations are .75 MOA or better. For my 6.5 Creedmoor rifle, my components are Peterson Cartridge cases, Nosler 140-grain Reduced Drag Factor (RDF) Match bullets, Vihtavuori N550 powder and CCI BR2 primers. My pre-loading process is minimal. New brass gets a mandrel and chamfer through the mouth, while fired brass gets dry tumbled, full-length sized, trimmed and chamfered. I clean the primer pockets of fired cases just because it makes me feel better. My bullet seating depth is .020 off the lands. I chose a powder charge weight based on a low ES number. My rifle has an NextGen EC Tuner Brake on the barrel, usually on setting “7.” The rifle shoots tiny groups and I have worked out many kinks in the rifle which makes it less finicky about load development.

Summary

There’s a great deal of satisfaction making ammo that shoots small consistent groups with low ES and Sd numbers. Hopefully these reloading recommendations offer a straightforward starting point for your precision journey. Understand, though, that load development can be an ongoing adventure, and that any changes to the gun or environmental conditions may require an ammunition rework. That is why I recommend sticking to the basics and documenting the results. Get a good baseline of how the ammo and rifle work together first and then you can introduce other elements. It will be easier to see if the additions improve your precision or not.