Ejection pattern, and therefore the speed/force of the bolt carrier group is a good indicator of what's going on with the gas system.
While a 3 o clock ejection pattern is considered "ideal" for operation of the weapon, it is worth nothing it sucks for the guy to your right on the firing line, hahaha. As such I actually prefer a 2 or 4 o clock ejection pattern, both or which are slightly higher carrier speeds than ideal. A bit of extra power isn't that much of a concern on a duty rifle which may face harsh conditions and enviroments. While many shooters poo poo the gov spec gas ports which are generally considered "over gassed", one has to consider that gov weapons are expected to be reliable in much harsher conditions than most casual shooters can imagine.
Worth noting that with a 1 o clock ejection pattern, usually found on SBRs with suppressors, one needs to be very careful with ammunition, as the straining on the brass is fairly high. You're basically ripping the brass out of the chamber while it still under pressure, and the brass has "obturated" the chamber like it is supposed to. Case head separations and related funky malfunctions are common with reloads of poor quality, so it's best to stick to high quality first time fired brass with those kind of setups as i've learned.