Gunsmith system requirements state that you will need at least 6 GB of RAM. An Intel Core i3-4340 CPU is required at a minimum to run Gunsmith. In terms of game file size, you will need at least 5 GB of free disk space available. The cheapest graphics card you can play it on is an AMD Radeon HD 7850.
Gunsmith will run on PC system with 64-bit Windows 7, Windows 8.1, Windows 10 and upwards.