Reloading Basics: Substitutions
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- Last updated: 28/11/2019
Most shooters that make their own ammunition will use the same reloading components all of the time, having become familiar with particular brands of primers, bullets and powders. This is normally down to what is available at the local gun shop, particularly with powders which are very expensive to obtain by mail order, as most retailers stock particular brands of components. If your regular supply is interrupted by a market shortage or events like the recent ban of several powders due to a change in European regulations, you may have to change to a different reloading component and this needs to be done with care.
Of all the reloading components the primers seem to make the least difference to the performance of ammunition.
Over many years of reloading the author has changed the brand of primers used in both handgun and rifle ammunition with very little effect on the point of impact or muzzle velocity of the rounds. A recent test of some RWS primers did show them to be far more consistent than other brands, in terms of the muzzle velocity of the handloads, but other than that there seems to be very little else to differentiate between the common brands. It is very important however to remember that magnum primers cannot be substituted for standard primers, and vice versa in any situation. Magnum primers generate a much hotter and larger source of ignition and this has a significant effect on how the powder charge burns.
Some brands of primers are also harder than others and this can sometimes result in light strikes, particular in guns with a very light hammer spring. In the good old days of competitive handgun shooting, when the pistols were very highly tuned, shooters favoured a particular brand of primers that were comparatively soft. This does not seem to be such an issue with rifles and the author has found all currently available brands of primers to work just fine in a variety of guns.
As a general rule, it is not safe to simply substitute one powder for another. There are numerous powder burn rate charts available which show the comparative burn rates of different powders but this detail is provided for information only. All of the charts contain a warning that it is not to be used to calculate loads and you should not be tempted to substitute a powder for one that appears near to another on the chart. If you do need to change powders then you can use one of these charts to guide you to a similar powder, but you must then use the specific reloading data for that powder. Under no circumstances should you simply use the same charge weight as you were using with the previous powder and hope for the best.
For any given weight and calibre of bullet there are different makes available and it is fair to say they are generally ‘similar’ in many respects. This similarity is why it is so important to always keep your bullets in their original packaging, so you do not get them mixed up and use the wrong bullet in your loads. Bullets of the same weight, but from different manufacturers, often differ in shape and length and this will affect the Cartridge Overall Length of your rounds. Increasing the C.O.L. of your ammunition can cause issues with chambering rounds and shortening it will cause increased chamber pressure. If you do need to change to a different bullet of the same type and weight then always check the length of the new one and its effect on the C.O.L.
While the external dimensions of cases of the same calibre may be the same from brand to brand there can be a significant difference in the internal volume. It is the internal volume of the cases that is the important factor here, as it is the space in which the powder charge has to burn and generate pressure. Confining a given powder charge to a smaller case volume will generate an increase in chamber pressure with the potential for it to reach dangerous levels.
A very quick and easy way to check and compare the internal volume of cases is to simply fill them with water and weigh them. To do this you take a case and completely fill it to the rim with water and place it on your powder scale. Fortunately, it is very easy to convert the weight of water to volume because one gram of water occupies a volume of one millilitre (one of the few benefits of the metric system!). By comparing the volume of water that each brand of case holds you can identify which are potentially suitable for swapping to, and which are not. Any change in volume will have an effect on internal pressure, the larger the change in volume, the bigger the effect will be. If you are changing to a different brand of case, and the new ones have a significantly smaller internal volume, it is well worth reducing the powder charge by a couple of tenths of a grain and checking the muzzle velocity of the ammunition you make. Checking the internal pressure isn’t possible but a change in velocity, with all other things being equal, is a good indicator of any significant increase in pressure.
Having considered some of the potential pitfalls of changing to different brands of reloading components, it is important to remember that none of them mean that you cannot make any changes, you just need to take precautions and consider what you are doing carefully.
The key to keeping safe is the vast array of reloading data available today. All of the powder manufacturers publish data for their products, online and in printed form, and they almost all include details of the primer, case and bullet used to calculate that data. In addition to this, most of these manufacturers are very helpful and respond to questions quickly. Both Western Powders (Ramshot) and Sierra Bullets have first class technical advisors and they are well-worth emailing with any queries you might have.
There are also reloading manuals that bring all of the data from different powder manufacturers together in one place. Lees Modern Reloading manual is a great example with over 37000 loads and it also includes loads of information about pressure. With so much data for each calibre all on one page it is much easier to compare them and choose the most suitable one for your particular needs.
Another way to check the safety of any changes you are thinking of making is to use some of the reloading software that currently available, the author uses QuickLOAD but there are others available. This software contains a huge library of data on reloading components and it is very easy to ‘design’ a load for your chosen calibre. At the touch of a button it will calculate velocity, pressure and a host of other data for the load you have put together. You can also tweak factors like C.O.L., case capacity and powder charge and see the effect on pressure. With the QuickLOAD programme the pressure figure is shown in a gradually more noticeable colour as it approaches dangerous levels. Software like this is a great way to help keep things safe and it is well worth spending some time playing around with it. You can learn a great deal by changing the data you input and seeing exactly how it alters the velocity and pressure of the load. It is worth remembering of course that you cannot rely on this data entirely and all of the reloading software packages include disclaimers to this effect. Reloading data is your first port of call, the software is good for checking out the effects of changing that data, and test firing is the ultimate test.
Reloading is a hobby in itself and what makes it interesting is the fact that you can customise your ammunition to suit your needs, changes in what components are available in the shops and of course safety.
As anyone who reloads for the 45-70 Government calibre will know, there are different safe pressure levels for different types of gun in this one calibre and a good working knowledge of what will, and what wont, be safe in your gun is vital. Substituting one ‘safe’ powder for your class of 45-70 with another similar powder could just take you over the safe pressure level for your particular gun and put you at risk. The new powder may well appear in reloading data under the heading of 45-70 Government, but it might only be suitable for the higher-pressure guns. Software like QuickLOAD is a great additional level of safety and is well worth the initial cost. It is also a great tool for learning about the effects that variables like C.O.L. and case capacity have on pressure. There are more than enough sources of data out there to ensure you are working safely when reloading, you just need to take the time to familiarise yourself with it, take the necessary precautions and always air on the side of caution.
Ramshot powders, PPU Bullets and HK brand primers; Henry Krank & Co Ltd: henrykrank.com
QuickLOAD software; JMS: jmssporting.com
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