I just bought a used 3rd generation Glock 17. Paperwork shows it is less than a year old, and looks to be well taken care of. I went out to the range with a couple hundred rounds of ammo (after cleaning the weapon) and at about 150 rounds I got a face full of what felt like sand(powder?) after pulling the trigger. The weapon had fired. After making sure that I still had both eyes (I had taken the safety glasses off after firing a magazine to ensure the weapon was safe), I pulled the slide back and ejected an empty shell. (I tried to find that particular shell, but it fell into a pile of them and I didn't notice any with irregular marks/deformities.) I don't know what caused the malfunction, or what it was that hit my face. I was shooting the cheap Winchester ammo from Wal-Mart. After the malfunction, I fired another 50 or so rounds, and then a few days later another 200 rounds with no other problems. Is it more likely a problem with the ammo or the weapon? What shot into my face? My first time pulling the trigger on the M-16 in basic training, it jammed (missing extractor spring it turned out). That shook my confidence in the AR platform and since then I have never trusted it. With Glock's reputation for reliability, I'd like to know what happened so that the first impression doesn't stick. Thanks.