tom, it could be you have a sticky firing pin. Just this past Sunday my friend and I were out shooting and he brought his new Savage bolt and his Rem. pump out. During our last session a few weeks ago, he had a mis-fire with his savage. He had one again this weekend. The primer was indeed dented. I took that round and put it in his pump and it fired.
When he got home, he flushed out his bolt on his savage and found that it was 'gummed' up. He never cleaned the guts of the bolt.
I would try flushing your bolt with gun scrubber, let it drain, flush again, drain - then LIGHTLY oil. Use just enough oil to put a thin film on the parts to prevent rust. (WD40)