How can I see if this patent is in use?

I have an idea for an assault rifle that uses an air shock design that helps with the kick. I’m not going to explain much about the design, all I want to know is if there’s a website I could go to, to search if my design is already patented/ in use. It’s really important. I need to know if there’s a website that I can go to that helps me search the U.S patents for my design.