Go to your local hardware store and buy a 7/8" furniture leg cap. your choice of color...
You may have to warm it up a bit to initially get it to fit, but it will.
7/8" rubber, shaped to please, hold the vinyl. Get some.
On one of my rifles, a slow cycled eject would result in the case hitting the knob, doing a perfect 180 in both longitude and latitude thereupon landing back in the port fully ass backwards ready for impending chaos! LOL CRF my ass!