That's a lever and bolt from a lever action rifle. I don't know what kind of rifle. Looked at a bunch but no matches. Here's a diagram for a Winchester M92. Note the similarity of the lever with the oblong hole. Gary
Here's a pic of a Winchester M1886 breech bolt. Note the similarity to your bolt. The cut out areas are where the locking bolts come up from underneath to lock up the bolt. Not much doubt in my mind that you have parts of a lever action rifle. Gary
Most people only think of rifles such as a Winchester 94 , when they hear " lever action."
Many old rifles operated like this one in the video. I do believe that yours IS a part of a rifle, similar to this Sharps.