Beltfed762

Just bought a used GSG 522 SD and so far I love it. I have noticed that with the magazine inserted I cannot get the bolt to go forward. From the reading I have done, I think it's because I'm missing the bolt hold open spring. Haven't fired it yet so not sure how it will function but I do know that I need this spring. Looked around online and I think my best bet will be going to the Home Depot and finding one.