Disclaimer

This software is made available "as is" and is offered without any express or implied warranties as to performance, accuracy, fitness for purpose or of any other kind. No responsibility is assumed or implied for any result the user may obtain, or to any damage whatsoever ensuring from the use or misuse of this software or the database of possible inputs. Interior ballistic codes such as Artemis cannot calculate the exact pressures and velocities occurring in a firing, they can only provide a prediction. Artemis cannot be used as a substitute for conventional handload development where manufacturers guidance should be followed. Safe interpretation of the results requires that users are suitably qualified and experienced and will excercise sounding engineering judement and expertise.
Users are cautioned to satisfy themselves as to the accuracy and results of their analyses.

Why only a prediction?

A non-exhaustive list of potential sources of error between what Artemis (and other codes) predict are what actually occurs during firing:

• computational: every effort has been made to validate the Artemis code. This includes extensive use of Artemis to test it, including running a wide range of simulations and comparing experimental results and reference results available in the literature and checking that the effect of changing each variable is as expected. In addition, a large suite of automated tests have been developed that are run every time Artemis is modified; these test both individual functions within the code and the behaviour of the code as a whole, comparing its predictions to known results. However, it is impossible to guarantee that the code will behave correctly for all possible inputs. Even if the code that performs and outputs the calculations has been written perfectly, it uses several external libraries and is compiled to machine instructions by a compiler, the website is generated using an interpreter running on a server which is then displayed by a browser: the compiler, interpreter and browser are three very complicated programs with 10's of millions of lines of source code, each.
• assumptions: Artemis uses well established empirical rules to calculate factors such as the pressure gradient within the chamber and the energy lost as heat to the gun. If the characteristics of the gun being simulated is highly unconventional then these empirical rules may become unsuitable.
• user error: for example, if a spherical grain with a diameter of 1 mm is specified as a 1 inch diameter sphere due to an error selecting the units then the real burn process will proceed far, far faster than predicted, leading to far, far greater pressures and a higher muzzle velocity (or chamber explosion).
• input error: the input values used can only be best estimates, the most that can be expected is that they can be approximately right. If the true properties of a firing, such as the propellant's burn rate, substantially differ from these best estimates then the pressures and velocity during the firing will be very different to those predicted. A dramatic example of a factory made ammunition behaving unexpectedly, possibly due to propellant degradation, is demonstrated by Kentucky Ballistics here. Any interior ballistics code using the expected values for this propellant would't have predicted pressures exceeding 85 kpsi that caused this accident.