I read the "gap" thread pinned above and didn't pay much attention to it because the numbers seemed to be insignificant. Unfortunately, I found out the hard way there is more side to side slop than is mentions above.

How much side to side slop is there?  About 1/8" side to side movement. This is nearly enough slop for the selector to rotate on top of the selector stops (with trigger/disconnector removed).

A regular selector shaft is about .75" wide where as the CASS center shaft is about 1.125" wide.

I know you made it wider to accommodate the dove tail sections but, you might want to warn potential customers about this difference...

1/8" side to side (assuming you mean perpendicular to the receiver wall) movement seems excessive, the safety should not move much side-to-side except for how much the safety detent is allowed to move inside the detent groove.  If it moves around that much, it could mean you're not getting full detent engagement with the safety detent groove.  First try manually compress the safety spring and detent into the safety groove and see if the slop goes away, if it does, it is your spress pressure.  You can shim the hole in the pistol grip by cliping off a few coils of another (spare) safety detent spring and put it on the bottom of the spring hole in the grip.

As for OVERALL cylinder (shaft) length, tt is not an apples-to-apples comparison if you're talking about the safety cylinder (shaft) length on a single sided safety vs. the ambi safety as the single sided do not have to worry about the other end protruding enough to clear the receiver wall.  The BAD-CASS also have male dovetail protrusions to engage the femail dovetail on the levers.  It has to go far and beyond the receiver wall in order to engage the levers.  Due to these factors, the "overall" length is longer.  However, the gap (distance) between the inner (under side) surface of the safety lever to the receiver wall, is what you ultimately measures and care about. 

Everything indexes off the cente liner of the detent groove of the safety selector as that's where the safety detent engages the safety selector cylinder and determines how much the safety lever will stick out (or in) of the receiver on each side.  Measuring overall length isn't everything.

The measurements you have seems off.  Many forged receivers are 0.78-.79" thick, if the cylinder is only .75" long and evenly centered in the lower, the left side lever will never stick out far enough to operate.  The cylinder would be offset to one side, allowing the single side safety lever to be free of binding against the receiver wall...this means the right side (no lever end) would be regressed into the receiver.

There's a 1/8" gap between the base of the dovetail and the receiver wall.  There's about 3/16" movement (side to side) when installed.

I tried the selector on several ARs (plus measured the other two selector shafts) and they were all the same. Saying the side to side movement is excessive, is an understatement... I suspect the reason they made the selector shaft 1/8" too long was to accommodate billet receivers.  

There should be a warning in the description to save a lot of people like me, the grief of having to return this stuff.

I returned all three selectors for exchange with standard (non-cass) selectors.

Send it in and we will take care of it.  Ask for Tyler in the RMA department.  Thank you.

Thanks but, the problem isn't with the selector, it's with the fact that there's no warning/notification that the cass cylinder is extra wide.

All three units have been returned to the retailer (and the retailer was gracious enough to replace them with the non-cass version).