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Rocky’s Reloading Room |
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The 95% Solution: Benchmark To Reloading Success
One of the most common questions I get goes something like, “If I change to magnum primers, or a different make of bullet, or a different lot number of powder, do I really have to go back to Start loads and work back up?” The answer is “Yes” — but also “No.”
Changing components has been absolutely proven beyond any doubt to change the way loads shoot. The change might be in velocity or accuracy, but more importantly, also in pressure. So backing down a bit -especially if your previous load was on the warm side - is vital. The key words there are “a bit.” Backing all the way down to Start loads is safest, but working slowly back up might waste an awful lot of expensive components, not to mention the time it takes or the wear and tear on the gun. So how far do we really have to back off in order to re-test? Without a known test point, we cannot tell.
I long ago came up with a concept I called the “Benchmark Load.” The concept was to use a benchmark similar to those used by surveyors. That is, a single precisely known spot from which all other locations could be measured. But since Hodgdon came out with an excellent powder named “Benchmark,” I had to dream up a new name for my idea to avoid confusion. So from now on, I’ll call it “The 95% Solution.” For convenience, we’ll sometimes abbreviate it as “95S,” okay?
Here’s how it works. The concept is to have a fully documented load that is ALWAYS safe, even if you switch components. When you do switch components, you can match the performance of a load using that switched component with the known load, and know right away if the new component delivers less, the same or more velocity/pressure. That known (benchmark) load is The 95% Solution.
Here’s how you find it. Once you have a preferred or “pet” load worked up with a given list of components, write down EXACTLY what all those components are. List not only the maker but even the lot number of every component (if you know the lot numbers). List the brass, the primer, the powder and the bullet. Also record exactly how that load performs in a given gun. As a minimum, list the average velocity, extreme spread and standard deviation. If you can measure the pressure, record that average, ES and SD as well. The least important number (for this use) is the accuracy, so that’s optional. Do this for every single cartridge you reload. Much of it is probably in your load notes already, except for lot numbers. You now have complete data for your pet load.
To establish your 95S, you simply take your pet load, with the exact components you listed, and decrease the powder charge to 95% of the pet load’s charge. Yup, that’s why it’s called The 95% Solution. Note that we are NOT talking about a load that’s at 95% of the book maximum charge. We want a load with 95% of the powder in your favorite or “pet” load. Read that again. It’s vital.
Now load and fire at least ten of the 95S load. Carefully record every performance number we talked about before for velocity and for pressure if possible. Again, accuracy is unimportant because the 95S isn’t a load we’ll be using in the field. The more 95S rounds you test here, the more reliable will be the performance numbers, but ten is a minimum.
When the time comes that you have to buy a new box of bullets or another can of powder, or switch any other loading component, the first thing you do is to load up ten rounds using the 95S recipe – but with only the one new component changed. (It’s pointless to do this if you change two components, because you have no way to tell which of them causes any change in performance.) With that single substitution, test and record the performance numbers. You can get only one of three possible results: the performance will be the same as the 95S, less than the 95S, or it will be higher.
If the performance of the test load is the same as the 95S load, you can simply go back to your pet load and KNOW that the new component changes nothing. This is the ideal situation, and you were able to determine it with only ten test shots. Isn’t that great?
If the performance of the test load is less than that of the 95S load, you know that you could go back to your original pet load with the new component and use it safely as is, OR you could work up a bit from the old pet load. (Here is where accuracy comes in as a decision point.) That might require a bit of extra testing, but you know that the change of components is safe. That’s almost as great.
The real value of The 95% Solution is when the performance of the test load is higher than that of the 95S load. Here, you immediately know that changing that one component might have made your pet load dangerous. BUT, you learned it without having to fire even one high-pressure shot. Your options are to work up slowly from the 95S, or possibly to make the 95S your new pet load with no new workup needed. Learning that without firing any dangerous shots is the greatest thing of all.
So now what? If you did additional workups to establish a new pet load (because the new component delivered less or more than the old 95S load), you now need to establish a new 95S. The good news is that you may already have it. If the tests weren’t that far off from your old 95S numbers, just record the performance of the test load, and that is your new 95S load. If you had to make significant changes to establish a new pet load, just take the new pet load, cut the charge to 95% and test again for your new 95S. Simple; and it still uses only a very minimal expenditure of expensive components.
To help illustrate how to record the data, here’s a fictional 95S load chart by an imaginary reloader who owns a strain gauge pressure-sensing system:
223 Rem – SAAMI Max 52,000
Note how the change of powder lots in 4/07 had no effective change, and so the original pet load could be used as is. But, when the bullet was switched from the 50 TNT to the 50 Nosler Ballistic Tip in 8/07, velocity and pressure went up substantially. Because the 95S load with the new bullet equaled the original pet load in velocity, it could safely become the new pet load – despite the somewhat higher pressure, which is still under maximum. But a new pet load necessitated a new 95S load, the data for which is in the last line.
The important thing is that our imaginary reloader didn’t blithely substitute the Nosler for the TNT using his original pet load charge weight of 27.0 grains. There’s no telling how high the pressure might have been with that load. Instead, he learned that it would have been very high without ever firing a dangerous shot.
A good tool, this 95% Solution, eh? |