7 out of 7 magazines failure to feed - Thermold HK9110762X51 HK-91 7.62mmX51mm 10 Rd Black Finish

I tried these magazines in my PTR 91 and my friends HK 91 all chambered the first round but would fail to load a second in the chamber. The bolt would hit the round before feeding causing damage to the casing. Original HK magazines and the one shipped with my PTR worked flawlessly.