Currently I have 20 mags of M855, 5 mags of M193, 6 mags of 64 gr Winchest Ranger, and some mixed mags ( M855/M193, M193/Tracer, M855/Tracer, etc.)  Should I keep the same load, or should I mix some of all of them in mags?  

Keep mags segregated in that respect.

Different ammo has different points of impact and terminal performance.

Wouldn't want to be engaging targets wondering where my POI is going to be with the next shot or what I happen to have chambered...

Speaking from experience the tracers always hit low becauce the tracer is a long bullet and takes up alot more case space so there is less room for powder. Mixing the from the extremes, M855 tracer with M193 ball will result in some very confusing POI issues. Loading a single tracer near the end of a magazine is a good way to let yourself know it's time for a reload. Loading the last three is a bit too obvious, so one somewhere in the last five rounds won't really clue anyone in. If you're worrying about a combat mix of ammo, you're probably going to be in a firefight and the enemy is probably going to know where you are. One thing I was taught was to mix API and ball in the same magazine because when you light up a vehicle, you want it to light up. Most of the time all we got was M193 so the tracers were left to the MG's with the one in five combat mix. Bottom line is that the POA POI issues from 200 meters on in aren't enough to really affect your combat zero, no matter what your mix of ammo is. Anyone who makes this their paramount combat issue isn't living in the real world.

Thanks, that answers my question.