An Easier Method of Reloading for Performance

While there are some financial gains to reloading your own ammunition for your centrefire rifle, the primary reason for reloading is performance.  Performance may mean different things to different people but everyone will agree that accuracy is a component of performance – even people shooting large targets at short range will have some accuracy requirement.

What is accuracy?  Accuracy is consistency.  Everything happening exactly the same way every time.  We squeeze the trigger the same every time, we hold the rifle the same every time, we aim at the same point every time.  We have things to assist us do this – bipods and shooting bags, rifle scopes that magnify the target and crisp triggers.  But how do we get consistency out of our ammunition?

When a cartridge is fired there is a harmonic wave that travels through the firearm.   It isn’t just the consistency of this wave that is important – the wave has to be at a ‘node’ when the projectile exits the barrel.  I’m still researching the topic myself so I’m not 100% sure on the finer details, but I know that by modifying components of your ammunition will change this harmonic and change how the gun shoots.  Changing your projectile, case or even the primer will change the harmonic wave.

There are two main ways the reloader can modify their reloads to manipulate the harmonic – by varying the amount of powder the cartridge holds and by changing the seating depth of their projectiles.  Most shooters do this in tandem – they will create a grid with one axis being powder weight and the other seating depth.  My argument (and the point of this article) is that this system of cartridge development is flawed – modifying either of these variables does the same thing.  To achieve excellent accuracy by manipulating the harmonics only one of these two variables needs to be changed.  If you get your cartridge to the ‘sweet spot’ you’re at a harmonic ‘node’ – modifying the other variable is only going to move you away from this sweet spot.

So varying the powder charge of the cartridge will vary the bullet speed – more powder means more velocity. Increasing your powder charge also decreases the size of the air gap inside your loaded cartridge – smaller air gap means a more consistent burn and consistent velocity.  So it makes sense that, for the best performance, you want as much powder in the case as possible without excess pressure.

The highest pressure is always when your projectile is seated very close to or into the rifling.  As you space the projectile off the rifling pressure decreases (within reasonable constrictions).  So when developing a safe load, it makes sense to start with the projectile close to or on the rifling and work back.  

I never recommend loading cartridges with the projectile so far out of the case that it is forced into or contacts the rifling when it is loaded into a chamber.  Some people claim that certain guns, certain cartridges, certain chambers or certain projectiles only shoot accurately when loaded with the projectile seated into the rifling.  In my experience, secant ogive projectiles and chambers with short throats do shoot well with the projectile seated into the rifling, but this is only mitigating their design faults and usually there are a combination of errors causing this fault.  My answer to this is – change your projectile.  

I don’t like seating projectiles into the rifling because if you need to retract a cartridge from the chamber there is a good chance the projectile will stick in the rifling.  The case will come out and spread powder through the action of the gun, prematurely ending a shooting trip.  I don’t like seating projectiles close to the rifling because there are tolerances in all the components of your reloading components and equipment – this can mean there is a couple of thousands of an inch variation on your seating depth of your projectiles.  One projectile might be seating a thou’ or two off the rifling, but the next might be seated a thou’ or two into the rifling – this can create excessive pressure and increased velocity which changes the harmonic wave and reduces consistency.  If you have one projectile 9 thou’ off the rifling and one 11 thou’ off the rifling it won’t make a huge difference in pressure and velocity. Typically, I start my reloads ten thousandths of an inch off the rifling and work back.

Step 1 – With the projectile seated ten thousandths of an inch off the rifling, I make up a series of loads with increasing powder weight until I start to see pressure signs.  I then back the charge weight off a little (roughly half a grain for most high powered rifles).

Step 2 – Using the same weight of gun powder I load 8 cartridges at the following seating depth –

• 10 thou’ off the rifling
• 40 thou’ off the rifling
• 70 thou’ off the rifling
• 100 thou’ off the rifling
• 130 thou’ off the rifling

I shoot two groups of each load, with each group having 4 shots in it.  Why four?  Because if one of the shots was an obvious mistake on the behalf of the shooter you can discount one shot and you still have a 3 shot group and a 4 shot group to judge group size.

When you are chasing nodes on the harmonic wave there is little point in making small changes in seating depth.  You are chasing a node in the harmonic wave – thirty thou’ jumps will get you near and past a node. Once you have found a seating depth close to a node you can do several more loads either side of that one to milk the last of the accuracy out of it.  This method will save you making twenty five or thirty loads and waste two hundred and fifty rounds chasing a node.

Tips for reloading for accuracy –

• Buy good quality dies, especially neck sizing dies and bullet seating dies.  Seating your projectiles perfectly square and to a certain depth is essential for optimal accuracy.
• Buy a Hornady Lock and Load cartridge length measurer with the appropriate modified case for your chamber.  You cannot get measurements precise enough to make accurate and consistent reloads using any other method in my experience.
• Measure your cartridges from their base to the ogive of the projectile – not the overall length of the loaded round.  Your reloads will be much more consistent.
• Load your cartridges with bullet jumps 30 thousandths of an inch jump variations.  You will find the most accurate load faster and easier.