Howdy Pain,
I have an ASM Schofield that had a similar problem of one chamber not firing. I noticed that the primer strike was off center. A slow working of the action revealed that the offending chamber was not fully rotating into battery. Parts are hard (impossible) to find so my gunsmith and I determined that the hand was short (worn?). He carefully stretched the hand through peening. It almost completely solved the problem. Also try turning in the screw in the front of the grip to create more spring tension.
As far as opening on firing, mine has never done that, but the spring that holds the latch closed is very strong. Maybe a gunsmith can install a stiffer spring and/or adjust the engagement angles of the latch.
Reverend Chase