I had 5 loaded shells. I fired three-all OK -- 14.6 gr of H110.
The fourth case misfired. I tried to fire it 3 or 4 times with no results. The fifth load was an extra loud crack, increased recoil, but not terrible, the the lever was locked closed. After fooling around, I got the lever to open. Near the end of the stroke was a firm spot. The same on returning the lever to bolt closed position. It started out difficult to move, got over the hard spot, and then closed with normal effort.
I went home and pulled the bullet on case #4. The case was empty--powderless. This with the increased recoil and noise leads me to believe the case was doublecharge.
There is one thing I will do tonight I just thought about while writing. I will attempt to charge a case, no bullet, with 29.2 gr of H110 and see if it overflows or holds the powder.