question for a sentence in "English Patient"

[honhu]

I came upon these sentences in "English Patient" and could not for the life of me visualize the poses the author talked about. Please help!!!

"He has various postures with the gun--half-staff, half a crook for his elbows when it is over his shoulder"

the gun is a rifle

TIA

[JBI]

leaking on it with it facing down, or seeming to lean on it as it is under his shoulder facing forward.