Stan honestly I have not noticed any real issues.
The links in Stan's post offer a very clear explanation of the potential for inaccuracy with either commercial or homemade chamber gauges. If there was zero taper to a chamber, and absolutely zero tolerance in chamber dimensions of every gun you check, all would be fine. Unfortunately, that is not the case.
If your gauges lied to you because you were measuring a chamber that was very slightly out of spec, then firing 2 3/4" shells in a 2 9/16" chamber in a 16 ga. gun probably isn't going to cause any issues that you would notice. Even if firing the longer shells boosted chamber pressures by 1000 psi or so, it probably isn't something that you would feel or something that would cause immediate damage to the gun. But you would know as much about the actual chamber length as if you hadn't bothered measuring them at all.
