Hi Matt,
the CD40110 would do the job, but reset is always done by zeroing the outputs.
I understood you want to indicate the remaining rounds of ammo when the gun is loaded - 99 (instead of 00) and count down.
Therefor I suggest to use a programmable binary U/D counter (74LS192). That one can be preset and loaded to any value.
Using a CD40110 you would save one IC per digit (contains a 7-segment decoder already), but indicating a false value. Starting at "00" the first trigger pulse would set it to "99" which is acutally "98", since one of 99 shots is already fired. (or fire one shot without ammo before loading
)
To trigger the counter the gun has some means of triggering a "bullet". If it's electronic that would be perfect, using the same signal to trigger the counter.
If it's mechanical the easiest way to trigger the counter would be a tiny microswitch (or a reed switch, magnetically activated) to attach to the trigger.
Please decide on the choices offered and also make a short describtion of the gun trigger mechanism.
Hans