13/07/2020 | Hints from the experts
Erosion behaviour
Dear fellow shooters,
One question that comes up regularly relates to erosion and whether double-base powders are harder on the barrel than single-base powders. First, let’s clarify which powders are single- and double-base:
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|---|---|---|---|---|---|
| RS12 | X | ||||
| RS20 | X | ||||
| RS24 | X | ||||
| RS30 | X | ||||
| RS36 | X | ||||
| RS40 | X | ||||
| RS50 | X | ||||
| RS52 | X | ||||
| RS60 | X | ||||
| RS62 | X | ||||
| RS70 | X | ||||
| RS76 | X | ||||
| RS80 | X |
We know that erosion depends heavily on the flame temperature. Double-base propellent powders contain nitroglycerine and thus naturally have a higher flame temperature. For Duo RS50/RS52, the difference is around 125 Kelvin. For Duo RS60/RS62, it is approximately 250 Kelvin. RS52 thus shows greater erosion than RS50. The same holds true for RS60: it causes greater erosion than RS62. How much more rapidly does the barrel degrade with double-base powders? That is of course the question behind this column. According to our best estimates, double-base powders reduce barrel service life by 15 to 35 percent. Let’s look at a concrete example: With a single-base powder, the barrel will hold out for e.g. 3,000 rounds. When I use a double-base powder, this costs me 25% of the barrel’s service life. That leaves me with a barrel service life of 2,250 rounds. At this point, the long-range match shooting community will speak up and point out that they change their barrels after 800 – 1,000 rounds. That’s true, but not every shooter wants to put their rounds in the black at 800 or 1,000 yards.
The pistol community will also have something to say. Handgun barrels last considerably longer than rifle barrels. This is due to the lower total energy input. A charge of 4 grains in a pistol is just not going to develop the same energy as 45 grains or more in a long gun.
To sum up: Double-base powders deliver more power, and generally better temperature coefficients as well. The trade-off is a somewhat greater erosion. We adjust our powders to keep this greater erosion within acceptable limits. To get the maximum service life out of the barrel of their weapon, shooters must use a single-base powder, foregoing solely that last quantum of performance. I hope you find this information helpful.
Yours,
Dominik Antenen