Practical use of powder burn rate charts

[Marine24]

I've never got my head around the use of burn rate charts, even though I've seen them on a number of reloading and powder manufacture sites. I realize they shouldn't be used to develop loads but is it a good reference to use to select powder options?

I typically use Bullseye in my 9mm and 45 ACP loads, but based on similar burn rates, Titegroup and American Select would also be options.

Reloaders manual would be the deciding factor, but curious how others use burn rates.

[sellersm]

Well, IMHO, a burn-rate chart isn't going to make or break a reloader. There are many articles on the web that show how meaningless the charts are, and just try to find two or more charts that actually agree with each other!


With that said, there are some general principles that ARE illustrated by the chart. These are examples of some principles, taken from my collection of 'notes' gathered from various people/forums/articles:


A slower powder is required to safely and properly get velocity out of a larger, heavier load. .380 or 9mm would NOT be a good example. .357 Magnum is a fine example.


If you take .357 Mag and use a fast burning powder (AA#2, Bullseye, Titegroup), you can make target level loads with a very light charge weight. They can be accurate, economical and low in recoil. But to be safe and proper, they can't run really high velocities.


When you use a fast burning powder at the top end, the pressure curve is sharp. It doesn't build slowly, it rises very quickly to a peak and can get dangerous. It's EASILY possible to blow up a magnum revolver with a too-heavy charge of a very fast burning powder. Easy.


When you use a slower burning powder (Alliant 2400, AA#9, H110), your charge weight goes up -- in many cases, it goes WAY up. But the pressure curve is much more smooth and almost linear. You increase the powder charge and the velocity increases at a (somewhat) predictable rate. And where the fast burning powder hit it's peak in velocity (and safe use!), you are 200-250 FPS faster when approaching max with a proper slow burning magnum handgun powder.


There are some powders that are so slow that you practically have to fill the case as you reach max loads. Not so with fast burners. With some fast burning and dense powders, you can put three full max charges in one case and still seat a bullet. That's an atom bomb that will destroy any handgun.


The lighter the bullet: usually the faster the powder and the less the case fill.
The heavier the bullet: usually the slower the powder and the more the case fill.


Happy reloaders are those who generally match 90% max pressure with near full cases of powder and 97-99% burn completion for a given bullet weight/powder type/barrel length - But that's advanced reloading taking advantage of internal ballistic programs like QuickLoad.


Pick the middle of the powders listed top-to-bottom -- and the middle of lower half of the manual's Min-to-Max range of recommended powder load for a given bullet weight and you're in safe starting territory.


Remember:
- Accuracy and practice are more important than velocity in most hunting situations.
- And Never reload off a burn-rate chart.

[Marine24]

So true. Thought I could use the burn rate chart to find suitable substitute powders since finding my preferred ones is proving difficult, but might work in theory but not so much in practice. I typically use Ramshot TAC for my .223 and .308 loads and thought I could use it in my .338-06 ammo. Not so much.

210 grain bullet in my 338-06 load isn't a good fit for Ramshot TAC. Better option is to go with Reloder 15 for all three calibers, but if you looked at the burn chart, you wouldn't come to that conclusion.

[jerrymrc]

I will also throw a few things out there. BLC-2, AR2206, AA2460, H335, TAC, H4895 are all together on the chart. When I was working up a load to match my surplus Aussie F4 (loaded with AR2206) I found BLC-2, TAC, and H4895 did not work for me. AA2460 allows me to match the POI with the F4 and keep a good group. Not saying the others were bad but the load that made the best groups missed the POI and it was important to be able to switch between my handloads and the surplus.

I also load a slow AA7 for pistol just because it is impossible to double charge it. For me the argument that I only get 800 rds out of a lb vs 1200 is moot and is much less sensitive when using an auto dispenser.

[Madusa]

Use all the time. Mostly shotgun powder in handgun loads.

[Zombie Steve]

Finicky gas system guns (think M14), extrapolating data where there's little or none... I find the burn rate chart pretty handy.

Any given powder can be used in a lot of applications, but it's probably only going to do a few really well.

What's more interesting is that many manuals (Lyman 49, for example) will list their data for a given load from fastest to slowest powder. As you stare at the data, you see a burn rate that's optimal with the results they're getting, then if they get too slow, it starts dropping off again.

[SA Friday]

Burn rate charts are a basic tool. They don't really come into play except for comparing what should work and determining which powders to test to find for a new load. I rarely used them as a beginner reloader. Now that I'm experimenting with multiple calibers, they do help me narrow down the powder selection a little. IMO, the availability of load data on the internet and being able to learn from others testing has lessened the usefulness of the charts. They still have a place but they are a basic tool, not a precision instrument.

[spqrzilla]

The danger with burn rate charts is believing that they are saying anything more than relative position in burn rate. I certainly would not use one to extrapolate off of another powder's data to create reloading data by itself. And even at the basics of relative position in burn rate, the reality is that some powders behave differently than others as you move through different peak pressures (most of the reason that H110 /WW 296 behaves as it does).

So beyond figuring out a general use for a particular powder, or vice versa getting a quick idea of some other powder choices in a range of powders, I don't look at them at all.

[Zombie Steve]

Certainly I wasn't saying to look at the burn rate chart and start making up loads. But if you're missing one piece of the puzzle, they can help you in seeing trends. Rare, but this stuff happens.

Example - let's say you get some pulled .30 AP bullet or a solid copper bullet. It's 165 grains, but it's bearing surface is longer than most 180 grain bullets you have. You know you can't just use your normal 165 data. If you have data for this bullet and other powders, you can get an idea of how much you need to back off your normal 165 data by looking at how similar powders behave with this bullet. This has happened to me a couple times.

Again, the burn rate chart isn't going to be a rosetta stone for you. It's obviously not plug and play among different powders. You need to stare at data and have an understanding of what's going on. The burn rate chart is just a part of that understanding.