It's incredibly silly for it to be 10; what's the advantage of the
double homing missile launcher over the regular homing missile launcher
otherwise? It's just much slower and less versatile. Now it should
be slightly better, because you can effectively shoot 30 missiles
total, instead of just 20.
(Micro homing missiles are different; the advantage of having several
weak missiles instead of a smaller numer of strong missiles is
actually quite significant.)
The source code contains routines to initialise all these resources, but also
functions to load from and store to external files. Support for external files
has now been removed; this removes a potential difference between compiling
with or without USEPAK, and makes it easier to change missions in the code.