To help find my own reloads in the grass when shooting with others, I have thought about putting a dot of bright polish on the top of the bullet. Is this a no-no? Would a magic marker be recommended instead?
I agree with the Sharpie idea. At the IDPA matches a lot of the reloaders have their own color and way of marking the case. It's common to see people picking up their buddies brass and give it to them.
I also like the silver Sharpie for marking on the common black stuff involved with guns such as numbering mags and putting my initials on stuff.
I have multi colored sharpies I use for distinguishing different loads in the same box when I am working up loads for a new gun, I just mark a line on the bottom of the cases. It also help if a load starts showing pressure signs so you know which load it was when you have a pile of brass.
I go to the range twice a week and shoot 50 rounds a visit. After I reload and all the rounds are in the holders I lay a 6" rule on them and draw a line with a Sharpie. The line is across the primers too and one stroke gets 10 at a time.
Different day different color, then I show them to my shooting buddies who return all my brass (as I do their's). Rarely do I come home without all my brass and some extras from those who don't want it.
Tumbling removes the Sharpie lines.
I also tend to use brass with the same headstamp for each 50 that I load at a time. Right now I'm using Blazer, next week it may be Speer or PMC. This also makes it easier to id as mine.
Being a scavenger (cheap), I'll retrieve empty ammo boxes and holders from the trash can. All my reloads go to the range in the factory holders with the box turned inside out. I mark the outside of the box with the load data and the load date. It makes me smile when there is a $14.99 price sticker in a box that I bought 7 months ago.
Brightly colored sharpies on the casing head should help. I used them while shooting a National Match M-14. Casings could only be fired three times then discarded. That last reloading for the last firing was marked bright red so I wouldn't reload it any more.
I have to say Sharpees or even paint markers. Nail polish is a rather unique substance, predominantly plastic explosives (Nitrocellulose) in suspension. I would imaging if SHTF, some powdered nail polish could be useful as a form of gunpowder similar to black powder.