January 04, 2011
Having a plan will help you find the right load quicker.
If you're a handloader, part of the excitement of getting a new rifle or opening a box of new bullets or canister of the latest propellant is embarking on the task of taking it to the limit. That means finding out how good it can get. Whether this task is a chore or something eagerly anticipated varies with each of us. Either way, focusing your approach--having a plan--sure makes it go faster, and that usually means better.
There are different reasons a shooter might be faced with the need for load development. Anything new or different, whether it's loading components or a rifle (or a barrel), demands attention. When it's all different--a brand-new cartridge and brand-new rifle or barrel--you'd better get a brand-new notebook as well.
There are a number of good loading manuals. Most are published either by bullet or propellant manufacturers. Nowadays there's a lot more loading data available via magazines and the internet. Study enough of it, and it's plain that agreement is unusual. The reason for this is because of differences in components, equipment and testing conditions or circumstances.
If anyone ever wonders if lot-to-lot differences in primers, propellants, bullets and cartridge cases exist, I can assure you they do. So, for me, published data merely establish an idea of what bullet velocity I'll get for a given charge weight. And while that's an important function, every serious reloader ends up writing his own loading manual.
There are a number of variables that apply to a cartridge (propellant, bullet, primer, case), and then an increasingly escalating number of variables that can be introduced through variously combining and fine tuning all those (changing bullet seating depth, for example).
It is important to reduce variables to a minimum to get accurate feedback from testing. Given that, I'm going to focus on propellant charge for this article. Take this information, apply another variable, and the testing process still stays essentially the same.
Before starting the discussion, I want to point out that no trip can end without a way of knowing when you've arrived. In other words, what are your goals in developing a load? For some it may be speed. For me it's tight groups and no quirky behaviors--especially no pressure problems. Whatever it is, you need to decide what criteria, once met, will tell you you've found the load you're looking for.
Pierced primers and other warning signs do not lie. When you see them, pressures are too high and you need to back off.
It's best to start your load testing with new brass. The reason is that new brass gives a better indication of pressure than a fired case will. In most rifle chambers, initial expansion in new brass is greater than with fired cases.
It's going to be the primer pocket that tells you the most. Some people measure case-head expansion, but it's easy to gauge changes by feeling how the primers seat into the resized cases. That's the direct effect of expansion and a telling clue.
A hand-style priming tool is really necessary to get accurate feedback. If the primer enters the pocket more easily than normal, that's a very good indication the load is running hot. Admittedly, it is a subjective evaluation, and there has to be something to compare it to. That comes only from experience.
Judging fired primer condition is also a common means to gauge load pressure. I habitually look at the spent primer on each case that comes out of the rifle chamber during testing. In a load that's not over pressure, there should be a radius on the edge of a fired primer.
By starting development with new brass and a hand-held priming tool, with enough experience you'll be able to "feel" when pressures may be getting too high.
Not all combinations clearly reveal the visible pressure warning signs we watch for: excessive flattening, cratered surfaces, cracks or pierces. It seems to depend a lot on the primer brand.
Also, small-rifle primers generally do not show as many indications as large-rifle primers do--or at least they won't until pressure levels are comparatively higher.
One thing's for sure, though: If you see anything that looks like an over-pressure symptom in a primer, you'd better believe it's telling the truth.
Another clue to excessive pressure is case-head damage, usually seen in marks or impressions on the brass. Seeing an impression left behind by the ejector, for instance, tells you the case was driven back against the bolt face very forcibly. This can vary from rifle to rifle, but if you know what's normal for your rifle/cartridge combination, you will be able to tell if something's amiss.
Usually, though, the best immediate indication is bullet velocity. A chronograph really needs to be part of any handloader's tool set. It's the only way most of us can get numbers that reflect load pressures. If you're seeing more speed than "everyone else" claims to get, you'd best be backing off.
Do not, however, assume the combination you're testing is safe just because you're not getting as much speed as you think you should. There's a slew of reasons that some combinations may hit a pressure ceiling before they reach the speed goal, so always watch for pressure signs.
For NRA Highpower Rifle, I do load workups at 300 yards (unless it's a 200-yard load) because I like to test a load at the distance at which it's intended to be used. And in general I follow the Audette method, named for the late Creighton Audette. Many call it "incremental load development."
It's easy to find detailed treatments of this process, so I'll just overview it here. The sole variable in this method is the propellant charge.
First, establish a starting and stopping point for the charge weight. The range will be dictated by the cartridge you're loading and the propellant you're using; faster-burning propellants in smaller-capacity cases, for instance, will have a nar
row range between starting and stopping points.
It's important to control variables in the load development process and test only one variable at a time. Most shooters have a bullet, primer and case in mind. Then it's a matter of testing powders.
Then work up the charge weight in 0.20- to 0.30-grain increments and shoot the loads on a target--preferably the same target. Creighton did this one round at a time, but let's go ahead and shoot three per step.
As the propellant charge increases, impacts on target should get a little higher, and there will be points along the test that show tighter groupings. Ideally, there will also be a stretch where accuracy and elevation of a few sequential workups are coinciding: All the groups are small and contained in close vertical proximity.
Creighton said pressure symptoms define the upper limit and that looking "back down," as it were, on the progress of the incremental buildup will reveal an area where impact clusters are similar and pressures are workable.
Hopefully there will be at least two charge increments represented; more is better. If it's showing this, then choosing something from that sector gets a load that's accurate and not "sensitive," meaning that variations in temperatures and so on aren't likely to push it over pressure or hurt its accuracy.
That, again, is shown by seeing vertical consistency over more than one incremental workup. Choose an upper, lower or middle representative from this cluster; upper-middle usually appeals to me.
The author does his load workups right at the range, using C clamps to affix press and metered powder measure to a bench or table. This assures testing consistency: Try different loads on the same day.
That method sounds reasonable, and it is. But in experience it doesn't always work perfectly well--at least not with every propellant. However, it's something concrete to follow. If it doesn't work, then the next test should be with another propellant.
It's easy to modify such a method by going up in bigger steps, and I often do half-grain increments (fewer of them, of course). I also don't always start as low as some.
Any incremental test should at the very least show a step or two that deserves more pursuit, and then my test groups are 10 shots. Be warned, though; you can actually wear out a rifle barrel by doing a lot of testing. The better you know your rifle, and yourself, the fewer test groups you'll need to fire before you call it a day.
I want to see consistent performance over at least two 10-shot groups with any load before leaving the range. I might then also want to try a bullet seating-depth experiment because I've usually settled on a primer, case and bullet. Those things can certainly be the focus of another trip. Just keep it fair (to yourself) by staying in control of variables, and that means introducing them one at a time.
I usually take no more than two or three powders with me--even if I'm starting work on a brand-new cartridge. It's easy enough to get a pretty good idea, if you don't have one already, about gauging chances for success over a narrow range of propellants.
If the whole point is to test a new propellant, make sure you bring a propellant that you know works for a given cartridge so you can compare them in a single session. The reason is to make it a truly fair comparison, on that day.
I do initial workups at the range, so I load the cartridges right there. It's not hard to put together a portable loading tool set, and it's even easier to use. I take a cartridge carrier full of primed cases, the propellants I'll test, and a seating die threaded into a small press. I C-clamp the press and my powder meter onto a bench, portable table or even a pickup tailgate.
It's extremely important to calibrate the powder meter for the propellants you'll test. A meter with micrometer-style adjustment is mandatory. That way you can go up or down in charge weight without having to weigh the charges, which is difficult to do outdoors.
As long as you know what you're getting, a meter works just fine. I always write down the meter setting along with what the propellant charge weight "should" be and retain a loaded cartridge to take back home for a double-check.
I've not seen much published on this, but I am convinced it's best to stick to one propellant at a time to evaluate accuracy fairly. Clean the barrel before trying another propellant so firing residues aren't "mixed."
I will also say the same thing for bullet jacket fouling. If you stay with the same bullet brand you should be fine, but mixing brands with different jacket compositions may require additional cleaning and more shooting. With either approach the bullets will eventually settle in and group to their potential, but the number of rounds required for that to happen can vary. The first few to several will not give accurate feedback upon a switch.
Developing and maintaining a control load is the goal of all this work. Especially if you're a competitive shooter, that load is the one on which you're staking your score. It sounds cool to call it a control load, and I guess that's an appropriate label, but it's really the last result of testing. We all want to beat it, of course, and that's what the experiments are about.
Sometimes the idea is to adjust your control load to work with a different rifle. That's usually easy. Back off a full grain and move forward from there. Another thing you might want to do is try a different primer or bullet with it, and the same advice holds true--back off a grain to start (a half-grain is okay with a bullet change, if the bullet is the same weight).
One thing I always do is shoot that control straight away with what I tested (if I liked the result of the test). Different days give different results with any ammunition, but ultimately the control load is the one that performs the best day in and day out.
I judge loads by the worst group I see, not the best. I'm always looking for the best worst group, and I hope that makes sense. Keep looking, but don't be afraid to say it truly is the end of the road and be happy where you are.