It has fold marks and is folded and sealed at one end. The other end had no such fold. The longest part of unassembled rifle was just under 35" in length, how long was the bag?
There is a piece of tape running most of the length of the bag.
I'm assuming this is where the overlap/seam of the folded paper was stuck down lengthwise.
The long piece of tape is overlapped by two pieces of tape on one of the folds.
The length of all this tape from the closed end is about 30".
From the end of the tape to the open end of the bag there is no tape. I'm assuming the seam is left open.
This strongly indicates to me that whoever constructed the bag did it to carry an object less than 30" long.
I have to conclude this bag was never made to carry a rifle, assembled or disassembled.