Welcome to Northwest Action Works! Makers of custom rifles, barreled actions, and components for long range hunting and long range tactical shooting.
Load Development (Part 4 - OCW Ladder)
October 14, 2015
Welcome to the fourth and final installment in our basic guide to precision reloading. Now that we've covered all of the steps and equipment we use to put together high qualitey loads, it's time to go over how we go about deciding what to put in them!
Though load development is an enormous topic and one that is widely debated across shooting forums, this article is going to be quite a bit shorter than it could be. This is because the process we use is already very well described by its creator, on his website found HERE.
It is called the Optimal Charge Weight (OCW) method, and we have used it over and over again to find outstanding loads in a wide variety of cartridges. Dan Newberry gives very practical, easy to understand instructions for how to go about choosing a powder, how to safely find the maximum charge weight, and how to set up a series of test rounds for finding the best load for your rifle. If put together, fired, and interpreted properly you will end up with a load that will not only work great for the rifle you do the test in, but will often work well in multiple rifles of the same caliber. We have found OCW's for several cartridges that we are able to use for test firing our custom rifles and barreled actions, knowing they will nearly always give us a reliable measure of accuracy potential in a given rig.
Over the years of doing these tests, we have developed our own set of steps and tweaks to Dan's method that work best for us to consistently get the results we're looking for in as few range trips as possible. We recommend reading through Dan's instructions and getting a firm understanding of the process before reading the rest of this article.
First, we do what we call the "pressure ladder". Similar to Dan's description of finding the maximum charge weight, we consult the books we have on hand, as well as several internet resources in order to see what others are typically using for the given powder and bullet combination we are wanting to test. Once we have a pretty good feel for the higher loads, we build a string of loads at 0.5 grain increments, often extending to 0.5 to 1.0 grains above the highest load we've seen being used routinely. We then fire them in succession from lightest charge to heaviest, examining each for signs of pressure. (There is a lot of debate on the subject of determining actual pressure in a load and what constitutes a safe charge. In the end, we all have to research it and decide what we're comfortable with in our load development practices. Decide what works best for you and run with it!)
We typically fire the pressure ladder over a chronograph to get an idea of the velocities we're working with, and to look for consecutive charges where velocities are more consistent. We'll also often see a spike or two in velocity that we generally try to avoid running the actual OCW ladder through. We also usually fire them in 3-shot groups, and you'd be surprised how often you can start to see some good groups forming up at the more stable velocity levels.
Then we'll build the OCW ladder according to Dan's instructions, and fire it in round-robin fashion as he describes. One thing we'll do for a bit of insurance is load up 4 shots at each charge level. This extra shot has come in handy on several occasions, in a few different ways. The first is the most obvious, as an extra shot in the event of a called flyer. If everything is going along great and you get a flyer that you're pretty sure you caused, having an extra shot to stack right in with the other two can save the overall look and readability of a ladder. It can also serve to verify a suspected "scatter node" in an OCW ladder. If you have a group or two that just don't look right or you think might be a scatter node, putting another shot into them can sometimes answer the question. If we get a good ladder with a relatively clear result and have the extra shots left over, we'll sometimes take the load we believe to be the winner and the one above and below it and fire all three at a longer range. This can be a bit tricky if you don't have a pretty good idea of the velocities and how to compensate for the longer range, but we've seen 1/2 MOA 3-shot groups at 500 yards even with the completely different charge weights! This is a good sign that you are on the right track to a stable load.
One very important thing to note: follow Dan's advice and do not get distracted by the smallest group(s). Follow the method and do your best to analyze it according to Dan's method.
Once we have what we believe to be an optimal charge weight, the very next thing we do is a seating depth test in the rifle we're working with. We primarily shoot Berger bullets, and have had great results using their seating depth test method, found HERE. Time after time we have seen one seating depth perform a LOT better than the others.
If all goes well we make several confirmation loads and go out for long range testing. If we aren't seeing the groups we'd like to see at longer ranges, we'll step back in to shorter ranges to make sure groups are still fine there. Running several over a chronograph can tell you if you're getting some inconsistent velocities that would cause issues at longer ranges as well.
If you're having trouble reading a ladder or aren't sure you've picked the right load, Dan is a fantastic resource and will analyze a ladder you send him a picture of for a small fee. We've used his services several times and his trained eye can be a huge help when you've gotten too close to the project! Go through the consulting link on his page for more info on getting help from him.
As with all reloading advice, take it with a grain of salt and do more research before deciding on any one method or safety practices. Rifles and reloading are dangerous and you should not exceed your comfort zone with a great deal of experience or sound advice from people who have it. Be careful and ask questions if you have any.
Thank you all for following this series of reloading articles! Please check back soon for what we hope will be more frequent posts on all things rifles/shooting/hunting/reloading. Call or email with any questions!