Brake Rotor Dust Cap?

[Just a Six?]

So I finally decided to install the GM rotors & new pads that have been collecting dust for 3-4 years. The dust/grease caps fit nice & tight on one rotor & the other both caps are loose by maybe 1/32-1/64?
So can I just use a dab of silicone or glue to keep it on nice & snug?
These rotors came off a board member & included all bearings plus a metal-rubber Seal that goes onto the spindle 1st before any bearings. Never had one installed on my previous setup?

[Just a Six?]

 
Cleaned this up to make sense so Last question.
 
Tighten the nut on end of spindle for rotor & then back it off about 3/4-1 full turn before installing cotter pin correct?

[good2win22]

3/4 to 1 full turn is a bit much at least for me it is. That may leave some play between the bearing and the bearing race. I tighten the nut while turning the rotor.  This will help seat the bearings and seal. I will then back the nut off 1/4 to no more than 1/2 turn to line up the cotter pin hole.

[Just a Six?]

Thanks I knew it was somewhere less than 1 full turn.

[Just a Six?]

All done, set them to 1/2 turn from tight & they spin nice.
I used some Silicone on the Dust Cap & it's snug so it should stay on.
That's BS that I buy the $$ GM rotors & they have a tolerance issue like that but with the no name drilled & slotted rotors the caps both fit well.