AFAIK It's hard to find the proper duster at retail stores nowadays.
Industrial computer suppliers/warehousers will be able to supply you with this stuff but other than that most of the retail stores (Future Shop, BB, Staples, Costco etc.) that sell duster sell the wrong stuff.
You're probably better off with just running propane in your GBB unless it's imperative that you run duster (like KND said for rare pistols that you can't find replacement parts for).
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE