I agree with the above suggestion. You want to look into parent/child relationships. The parent should hold variables for all the gun specs you want to change (magazine capacity, fire rate, bullet type, cool down period, recoil etc). Then you create child blueprints off the parent and within each child you define the exact specs for each gun type. So AK47 will have 30 round magazine and a fire rate of 500 rounds/sec, but a barrett 50-cal will have a 10 round magazine and a fire rate of 1 round per second. A firing function within the parent BP will simply grab the variables necessary to determine fire rate and magazine capacity from the specific instance of the child weapon you have equipped. If you need to see an example of how to setup a basic parent/child relationship check out video #15 and 16 in the link below.