Seems silly, but I've got a Colt A4 upper with an M5 RAS. Is there a trick to getting the Rib rail covers on the top rail? They don't seem to want to clear the delta ring while sliding on. I haven't tried hitting it with my purse yet, but wanted to see if there was something I'm missing. They don't need to be up there, but I like the aesthetic and I've seen pictures with them installed.

It is recommended to not have covers on the top rail as they reduce air flow for cooling.

That said, like many others, I prefer to have them on.

I've had no issues with locking the bolt to the rear, pulling the charging handle back, and sliding on the rail panel covers from over the upper receiver and onto the rail.

Are you sure they are not getting out of alignment as you are trying to slide them on?  Are you trying to slide them on over the retention clip for the rear screw?  I remove those.

I dod not consider the retention clip for the rear screw. I see now that occupies the space the locking tabs on the covers would use. What effect on the rail does removing that tab have? I haven't dabbled with these until now

The tab retains the screw when it is removed from the rail.

I don't plan on removing the screw in a situation where it could be lost, so I remove the clip so that rail mounted items can mount over that area.

There’s really not any good reason to have one on the top rail, all you’re doing is limited your ability to attach items.

Don’t think I can help with install though.  Many moons ago, whenever we’d get a new batch of rifles in, we’d use a flathead to pry the top rail cover off to facilitate PEQ mounting prior to issuance and zero fire.  It was a lot easier than removing everything from the receiver rail to slide the cover all the way back past the delta ring and off the back of the upper rail.

Got. Doesn't seem too important to me either. May give it ago.
I always run something on top, on all my rifles, for heat protection. I wrap my thumb around the top and under enough volume, it warms up. I have Manta pic rail covers that will do fine if I decide not to force the KAC panels on, and they look good enough, but aesthetics are king here since it's not really a go-to rifle. More of a fun, for the collection gun. The only forward-mounted accessory it's getting is a flashlight and its mounted at the 9 o'clock.