Just thought I'd pass this along to everyone. Airsoft guns have a lot of screws that arent found in your average hardware store. I found this site while trying to replace those pesky little set screws in my PDI hopup chamber. Its called boltdepot.com, and they literally have any screw you could ever need. Whats more, they're really helpful and friendly: I talked with a guy for on the phone for ten minutes with him helping me figure out what I needed. They're located in Weymouth MA right outside of boston. Oh, and if you decide to search their site for the same screws I was (type 96 hopup set screws) the product number is 8700.
hope this is helpful!
hope this is helpful!