When your beloved 91-30 is leaning against the wall with the cruciform bayonet mounted, do not pick it straight up when you wish to caress or fondle it.
You will poke a nice cruciform hole in the ceiling.

Length of M-N with Bayonet = 5' 5"
Height of ceiling = 8'
Clearance to ceiling = 8' minus 5' 5" = 2' 7"
Distance from bayonet tip to place on the forend you will grab to pick it up = 3' 5"
Possible maximum depth of hole in ceiling when you pick it up, depending on the passionate impulse with which you desire to caress or fondle it = 3' 5" minus 2' 7" = 10"
Actual depth of hole varies according to your height, strength, and passion level.
Terry, 230RN