Load failed for me. I’ll try it later. Is this kinda like trying to de-cock a 1911 with your thumb?
I’ve tried that single-handed decock thing and it isn’t easy keeping your palm on the grip safety and decocking with the thumb at the same time.
No.
It occurs when you are loading the 8 round en-bloc clip (it IS called a clip in this case).
You rest the fat of your palm against the operating rod handle, and push down on the stacked clip with your thumb. On older rifles, really loose, worn, etc., the bolt will slam forward as soon as the clip clears the bottom of the bolt. The follower is all that is holding it open.
Normally, you just move your hand out of the way and let the bolt ride forward into battery.
Sometimes, though, the thumb doesn’t get out of the way fast enough, and wham.
I’ve never had it happen (lucky, I suppose), but it can’t be pleasent. The bolt is under strong spring tension, and in the “flesh versus steel” cage match, well, flesh ain’t gonna win.