"It's quite common to store those Model 99's in a decocked state via opening the lever, pulling & holding the trigger back while closing the lever slowly - but I've never recommended doing so with a live round chambered."
Slip closing the action will only work with rifles produced PRIOR to about 1950-1955 or so.
Around that time the action was modified. With that modification the slip close, which decocked the action, was no longer possible.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.