MAXAM reloading gun powders for rifled bore barrels
MAXAM smokeless powders are well-known and have been appreciated for many years by hunters and shooters worldwide for their cartridge reloading needs.
By publishing these ballistics tables and annexes, MAXAM continues to contribute to those who choose to use our smokeless reloading powders for rifled bore cartridges.
For the small private reloaders, MAXAM has now introduced containers with 500g.
Our powders are made from stable nitrocellulose in a gel form which then passes through a treatment to regulate their porosity. Then, through extrusion, they turn into circular or small square particles with medium-low gravimetric density (CSB, PSB+, and SSB+) or into small cylinders with hollow centres with high bulk density (GSB 146 and GDB 111).
The small particle size makes them easy to dispense.
Gelatinisation is done with a solvent that evaporates similar to CSB, PSB+, SSB+, and GSB 146, which are all single based.
For GDB 111, which is a double base powder, nitroglycerine is also used as a fixed solvent.
Combustion is standard and waste left in the barrel, with the correct dosage, is practically zero.
The main physical and ballistic characteristics are summarised in the following table using 12 gauge as the standard size reference.
The tests were performed in manometric barrels according to CIP standards, equipped with a piezoelectric pressure gauge and an initial velocity gauge.
The minimum and maximum dosage has been adjusted to obtain a pressure of between 75% and 95% of the CIP limit.
We recommend that you start reloading by reducing the dose by 10% of the minimum value.
Exceeding maximum values will lead to increased pressure above the safety limit.
Generally, as the shell size increases, the dosage increases.
With the same primer the ignition is greater when the shell and reload capacity are reduced.
Selected components have been used but it is very important to remember that different components along with barrels with different diameters or different lengths can generate significant variations in pressure and speed. Also this can happen if guns are used instead of test barrels.
The 9×19 calibre dosage can be adapted to the 9×21 calibre, but not vice versa.
At an equal maximum height and other conditions, the trajectory of the bullet before reaching the rifled barrel is lower for the 9×19 calibre and this implies that equal dosage gunpowder start at a lower volume compared to 9×21 calibre creating higher pressure.
In general, pressure increases depending on:
1. The primer’s power
2. The powder’s dosage and the shot weight
3. The sectional density of the powder
4. The charge density and depth of the bullet in the shell
5. The force exerted on the diameter of the bullet
6. The sectional density of the bullet
7. The ratio between the diameter of the bullet and the diameter of the bore’s rifled gaps.
8. The ratio between the bore’s diameter and the hollow sections of the rifled barrel
9. The relationship between the length of the shell inside the rifled barrel and its diameter.
10. The hardness of the bullet’s material and the friction between the bullet and the bore’s steel.
Increasing powder volume, because of a longer shell, does not always reduce pressure. It makes a bigger difference if the bullet’s path is reduced before arriving at the grooved barrel.
As a general rule, speed varies based on pressure increasing as the parameters indicated in points 1 to 5 increases and decreasing as the parameters increase as in points 6 to 10.
With all other conditions equal and with minimal deviations (within 5%), pressure percent increases in absolute values as well as the percentage increase in bullet mass and twice the percentage increase of gunpowder.
Inversely, pressure lowers as shell volume increases along with powder. If the powder dosage were increased, there is a similar absolute value but in an inverse direction in relation to the percentage increase of the powder volume available in the shell.
Inversely, if you increase the shot weight, speed decreases. For example, if the powder dosage and the bullet weight both increase more than 5% there is practically no variation in speed; whereas, the pressure would increase more than 15%. If the volume of the shell is also reduced by 5%, the pressure would increase by more than 20%. This would be the case if one were to change to a lighter shot to a heavier one of the same kind; for example, a 9×21 calibre using a 130 copper grain bullet instead of 125 zinc-plated grain, at equal total height of the cartridge, carries a mass increase of 4%.
The increased pressure, if the powder dosage is not at a maximum level, will also result in at least 7% but the speed will be reduced to less than 4% by the higher load density.
If you want to leave the pressure unchanged, you have to reduce the powder dosage to at least 4%, leaving the load density almost unchanged with a reduced speed of at least 7.5%.
It must be pointed out that these values are suggestions: in the case of large variations, the effect on the pressure will be much greater with could put the user in serious danger. For example, reducing the shell’s volume available for the powder will result in a non-linear, hyperbolic dependence. For the same gauge, using a heavier bullet must involve a significant reduction in powder dosage with a consequent reduction in speed. Alternatively, If you want to maintain speed, you will need to use a slower burning powder. In addition to increasing the powder’s temperature so does the pressure and speed; the effect is double the energy content of the propellant and the burning rate.
The opposite happens when the temperature is reduced.