Confused on Reload Function

I do have 3 variables (as shown below)
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The MaxMagCapcity holds the maximum ammo in the mag
the TotalAmmo holds the Total Ammo in the gun so thats the total of all the ammo in each mag
and the AmmoInMag is the current ammo being used. This is the one thats being decremented in my Decrement Ammo Count function.