I recently traded for what looks to be an earlier Gen 3 G21 with serial number starting CWK. The gun looks to have been used, but not abused. Function checks all OK. Unknown number of rounds, but I'd say up to 2K. took it out today and put about 60 rounds through it. Of those 60 rounds about 4-5 came back and hit me in the face. I came home and detail stripped and cleaned it, especially the extractor etc. The gun doesn't look like it's had any mods to it, however the extractor has no hump on the exterior portion like my 9mm's do. It is flat. I haven't owned any Glocks except 9's so I don't know if this is normal? So for those who know, is that normal? If so, any other ideas why this thing would be putting brass in my face? I thought earlier Gen 3's didn't suffer from this? Thanks!