That is something that should have been discovered when doing the first cleaning. I never fire a "new to me" gun until after a complete disassembly, and cleaning.
Firing from the hip sounds like a bad idea to me for the following reason:
Should you have a catastrophic failure, in most cases the shrapnel will go up and out to side. If you are holding the rifle low, there is more chance for serious upper body and head injury. By holding the rifle normally, you may receive wounds to the hands and arms, but in most cases the receiver will protect your head. I usually wear heavy gloves on the initial shooting of any used firearm just in case it decides to go kaboom!
If you are unsure of a gun's safety. Lock it down in a weighted bench rest or vise and use a string from well behind the gun on the first round.
With an SKS, I load one round and fire. If all goes as it should, I will then load two rounds and fire. If that goes well, then I will load a five rounds(controllable if it should begin slamfiring). Only after these tests will I fill the magazine.
