Metallic Reloading 101 - Part 4: Weighing out propellantsBy Craig Maylam
- 27th May, 2020 May 27, 2020, 11:49 AM
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We are marching through our reloading series and are now going to deal with a critical part of the procedure. As they say, this is where the pedal meets the metal - if this step is done poorly then you will find yourself in real trouble. As we have discussed earlier the powder burn rate is critical so please check this before you begin.
Good habit forming also starts now, so clear the bench of anything apart from the propellant you are supposed to be using, shut the door and keep distractions out (the Labrador who sleeps on your feet keeping them warm is an exception!).
If visitors call by while you are weighing charges then stop, deal with them, then resume weighing charges when they leave. This is not a process you can hurry and it is good practice to load ammunition in advance of your needs where possible.
The most important piece of equipment you will require is a set of scales. Spend as much as you can afford and purchase the best scales you can find. When you have finished with them for the session put them away in the carton they came in.
The carton will protect them from damage and dust that can cause them not to work properly. If you look after them you can expect them to last a lifetime. There are two types of scales.
These are commonly found. The beam is usually balanced on agate bearings with a weight that slides along its length. There is usually a coarse adjustment (normally 10 grains per division) plus a fine side with divisions of 0.1 grains.
To make the weight you want you build the weight up by parts. For example, to weigh 58.3 grains you move the coarse weight along to 50 grains and leave it there. Next you move the fine weight along to 8.3 and you have your charge weight. There are many different brands on the market and several different capacities that should you look at for before buying.
The first thing to look for in a beam balance is that it is made from metal. This will help with temperature based accuracy problems, polymer/plastic always grows and moves no matter which space-age resin it’s made of.
Second, you should look for bearings on the beam pivots. These will give your scale longevity and add to their overall sensitivity. The third thing to look for are knife-edged steel pivots on the beam. This is another feature that adds to the scales’ sensitivity.
A cover is also nice to have. A clean scale will weigh accurately. Without a cover, dust and other debris will accumulate in the pivots and destroy their accuracy and sensitivity over time.
One of the most important things to have is magnetic damping on the beam. Without this the beam will swing for an eternity before it stops.
The scale you purchase must be able to weigh down to 0.1 grains. This is a basic requirement. The RCBS 1010 unit I use allows me to further split that 0.1 grain measure again if I need to.
These are becoming increasingly common. They come in two types, first, a scale and nothing else, and second, a system that both weighs and dispenses the powder (propellant) charge.
The beauty of electronic scales is that you either set the weight you want and start the weighing process, or simply read the weight off the display. These are very convenient and both methods are accurate.
“Digital scales are temperature sensitive and need time to warm up prior to calibration, they are however very fast after that.”
I have used a Lyman powder dispensing system and found it both precise and simple to operate, but the system was slower for me than the beam balance scales I had been using.
Digital scales have real built-in strength which is handy for weighing heavier items like batches, loaded rounds and projectiles. Digital scales are temperature sensitive and need time to warm up prior to calibration, they are however very fast after that.
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Early digital scales were less accurate because of difficulties in producing an accurate load cell. Modern electronics and manufacturing techniques however have rendered this a condition of the past. Now you can expect a digital scale to be as good as a beam balance.
I have both - I use the digital scale for batch weighing and the beam balance for weighing individual charges.Scales run hand in hand with powder throwers, scoops and powder dribblers.
These look like a coffee grinder and dispense propellant volumetrically. There are many brands of throwers out there and all work okay, although generally the more you spend the better quality you get. The way to judge is to throw 20 charges with the propellant you want to use and see how much weight variation you get.
Propellant type is critical here; short stick, flake and ball powders will always throw more accurately than large stick propellants. Technique is important and practice will make perfect. A consistent technique will usually produce a consistent thrown weight.
A good technique will include an element of honesty where you dump a charge back into the hopper and start again if your operation of the handle was less than perfect. I have used a Hornady unit for many years and for the price I paid am more than happy with its performance.
Using scoops is an old way that has a lot of merit. Sets are available form Lee Precision and they are well worth their price tag. A scoop can also be made from a cartridge case, usually the calibre you are loading (so that the head stamp matches).
A strip of brass or a piece of copper wire can be soft soldered onto the side of the case to make the handle. To get the dimensions of your home made scoop right, the correct powder charge is poured into the case, which is then marked and cut down so that the powder exactly fills the case.
“A scoop can also be made from a cartridge case, usually the calibre you are loading (so that the head stamp matches).”
The correct technique for using a scoop is to put the powder into a metal bowl, drag the scoop through it until it’s full, then level the powder flat with the top of the scoop using a small ruler or knife.
DRIBBLER (AKA “TRICKLER”)
This is a useful tool that slowly dispenses propellant onto the pan on your scales. You could also use an empty cartridge case to slowly tip propellant with a twisting motion, but the dribbler is the most convenient method by far. Position the dribbler so that it drops powder into the pan while the pan is still on the scales, so that you don’t have to move it each time.
When you have weighed the propellant correctly you will need to fill each case. Two things make this easy, one is a loading block. These don’t have to be bought, you can drill holes in any old piece of timber.
It doesn’t have to be flash - its function is to order the cases so you can keep track of which ones you’ve filled, and also to stop the cases from falling over and spilling your powder.
The other thing you will need is a small funnel. These are indispensable if you want to avoid spills. Funnels come in either calibre-specific or multi-calibre. Calibre-specific funnels are great for small cartridges like .17 Remington and .204 Ruger. The multi-calibre funnels will do the rest without a hitch. An aluminium funnel will flow better than a plastic one, but they are hard to find now.
LET’S TEST SOME .270 LOADS
The best part of handloading is that you can tailor a load to your particular rifle. Part of this process involves the manufacture of test loads. These will have different powder weights so you can establish where the accuracy node is in your rifle. With the .270 we are developing a load using IMR7977. I found the following information in the IMR manual, see table:
|.270 Winchester, 150 grain projectile|
|IMR7977 – Start – 56.6||2717 fps||50,600PSI|
|IMR7977 – Max – 60.8C||2940fps||61,300PSI|
|(C = compressed)|
To test this combination in my rifle I will make a series of loads in steps, beginning at the starting load and finishing at the maximum. To decide how big each step should be, we need to fill an empty cartridge case with water and weigh what it holds.
A .270 Win case holds 67.0 grains of water. The steps for each increment in our loading sequence should be 1% of the weight of water, in this example that equates to 0.67 grains which I will round up to 0.7 grains.
“The best part of handloading is that you can tailor a load to your particular rifle. Part of this process involves the manufacture of test loads.”
The test loads should therefore contain the following charges of powder: 56.6gn, 57.3gn, 58gn, 58.7gn, 59.4gn, 60.1gn, 60.8gn.
This involves a lot of shooting if you are firing five round groups with each weight, so (apart from shooting just three-shot groups) what you can do is to drop a few loads from the sequence, or you can shoot a ladder. The ladder shoot involves loading one round of each propellant weight in the series and recording where each shot lands on the target.
The accuracy node will be where the majority of the shots land closest together. To fine tune the load you then re-test those weights using the method of increment above.
After dropping out a few weights from the series to save time and precious components. The test might look something like this: 56.6gn, 58gn, 59.4gn, 60.8gn.
For those who just want to shoot and are not too worried about extreme accuracy, you can go half way between the max load and the start load and make safe ammunition that will usually shoot okay. The charge weight in this example would be 58.7gn (max load + start load divided by 2).
Next issue I will be dealing with bullet seating and I will load up and test the ammunition.
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