Need easy answer to dumb question

[MTsmith]

I have both a 7mm mag and a 264 win mag (No, the question is not why do I have both). Some of my 264 win brass is made out of trimmed resized 7mm brass. Is there an easy (and safe) way of permanently marking the converted 264 win brass for easy identification?
I was thinking of filing the 7mm headstamp but didn't know if someone had an easier way.
Thanks for your help in advance.

 

[Catfur]

People have talked about notching rims to ID various wildcats, brass batches, etc...

 

[RT2506]

To ID cases made out of other head stamp cases I have just colored the head stamp with a fine point Sharpie pen. I have seen others just color the whole base of the case. I have also see others file a notch on the edge of the rim.

 

[cowboy]

You can use some cheap durable finger nail polish to color the base of the brass - lasts a long time and can be repeated when needed.