If you have previously uninstalled Gun Club then you would have also deleted all of your data (weapons etc) that was held on your device memory as we do not have cloud saves in Gun Club.
However if you follow the instructions below you might be able to retrieve your purchases from the app store that you purchased them from.
Depending on which platform and OS you are running, please find the information below:
Once you have re-installed Gun Club 2 and as long as you are logged in with the account that you originally made the purchases with you can navigate to the settings menu and press the Restore Purchases button.
This will restore any purchases made with that account. If you are running a device that does not show restore purchases in the settings menu, you can also try to repurchase a pack (without going through with the payment of course) because this can force the restore to occur, again though do not go through with the purchase or you will be charged again.
Just to reiterate though you must be using the original account that you bought the packs and/or items with or they will not restore if you don't have access to your original account there is nothing that we can do from our end unfortunately.