One of the most pleasurable parts of our journey is coming across folks who look at established methods and re-evaluate them asking if there is a better way. Load development is one of those areas where opinions and approaches vary widely. Shooting forums are replete with users throwing up groups and asking other users to interpret them because they lack an objective method.
We have been presented with an approach which we believe is objective and fact based, and corroborates some of the things that we have observed during our own load development. It’s an approach that we want to share with our audience for their consideration.
Many of our viewers are familiar with the Optimal Charge Weight (OCW) method popularized by Dan Newberry. Ed paid Dan’s consulting fee to help him develop a load and received valuable advice. Dan’s approach has lead us to some accurate loads, but there are some aspects of the approach that shooters should take into consideration:
- OCW does not account for variances in group spread attributable to shooter error. An OCW target resembles a dot drill and few shooters, even with the same load and unlimited time, can shoot a perfect dot drill. The round robin method, which is intended to reduce shooter induced error, may actually exacerbate shooter error because it resembles a dot drill exercise.
- OCW does not account for variances in muzzle velocity that may result in relatively tight groups at close distances but may open up at long ranges. Adherents to the approach are told to focus on group size and this presents a problem at longer distances as velocity variations lead to vertical dispersion. This is not opinion but mathematical fact – just consult your ballistic calculator. As such, velocity variations have to be taken into consideration and minimized.
Scott Satterlee, owner of Precision Tactical Solutions, paid us a visit to explain his approach to load development. Scott is active duty military and actually shoots for a living (some people have all the luck) and trains special operations personnel. His training is available to civilians – we took his training in December of 2013 and it was a game changer for us. But we digress…
Scott divides his approach into the following phases:
- Phase 1 / Step 1: Establish COL for your chamber where the ogive engages the lands. Back off .020″ from this length to establish a baseline COL for a starting load. There are a number of ways to do this. In the video Scott describes how to do this without using any special tools. Note: For VLD bullets we kiss the lands and call it a day. On Berger’s web site, some shooters are reporting better results when jumping VLDs but this seems to be the exception rather than the rule.
- Phase 1 / Step 2: Load test rounds, 5 cartridges per charge weight (start at 15% below target accuracy load and work up in .3 grain increments to 10% over target accuracy load). Target accuracy loads can be obtained from a number of sources, the most reliable being the gunsmith who built the rifle.
- Phase 2: Fire and chronograph test rounds in 5 shot strings without breaking your position. In other words, fire each group of 5 loads into one target before moving on and completely rebuild your position between targets. Do not shoot round robin, but instead randomize the order of the loads that you shoot. Allow time for your barrel to cool. It helps to bracket your reticle versus floating it over a dot.
- Phase 3 / Step 1: Identify the load group with the smallest SD/ES velocity variance and compare to POI spread on target. You will see a high correlation. Note: When we’ve used the OCW method in the past, our most accurate loads have always been the ones with the lowest SD/ES.
- Phase 3 / Step 2: Chart muzzle velocity groups and identify flat areas of the curve. Charting the results in a spreadsheet makes it easier to see the flat areas. You’ll want to find a load that is in the center of the plateau as it mitigates the effects of variations in powder charge, temperature, etc.
- Phase 4 / Step1: Load 5 rounds up and down from the optimal load by .1 grain increments to .2 above and below. Measure the velocity and group size to find the very middle of the curve.
- Phase 4 / Step 2: Once the mid point of the velocity curve is established, modify seating depth of loads (3 rounds) in .005 longer increments until the load is touching the lands. Note: VLD shooters who are kissing the lands already would eliminate this step. We advise against jamming the bullets into the lands as that can create a mess if you need to remove an unfired round from the chamber – the bullet will be stuck in the barrel and powder will get in your trigger.
In part two of this series we will use this methodology to evaluate several loads. Stay tuned!