This is a big fear of mine with 300blk and 5.56. I painted my 300 blks with red and yellow, as well as 300 blk specific magazine.
Amen. My 5.56 guns all have Ergo grips, and my 300blk has a Magpul K. I use metal mags on my 300blk and polymer mags on my 5.56. Even then I get nervous when I pack different calibers to the range.