The main body of the rifle/weapon into which the barrel is attached.
On the receiver
Turnbull
Metal
Look at the bottom of the rifle at the front of the receiver.
Receiver, stock, barrel, sights
Try the receiver
There is no one answer, as there is no one rifle. There are varied amounts of torque applied to a barrel screwed into a receiver, and varying amounts of torque created when a bullet is fired.
You will need a gunsmith to know for sure.
On the left side of the receiver.
Bottom of receiver
Check the receiver, barrel
CHeck the frame, receiver and barrel.