Yeah, I encountered the same problem when I attached my tacstar to the reciever of my 870. My 870 is a synthetic home defense model. I took the forearm off and cut out notch, so that the pump wouldn't catch on the tacstar. Then, I sanded the rough edges off. I don't remember the exact measurements for the notch, so measure the amount of space you'll need, and cut away with a hacksaw. Worked for me! However, it later became obsolete when I bought my Surefire pump.