Not only breathing issues but sunscreen and chap-stick as well. I forgot about how much more intense the sun light is at that altitude. Had to make a late night run to WallyWorld to find some.
When I started CAS 10 years ago I used AmmoDirect on-line to purchase and reload ammo. They used Top Brass for 45 Colt. I still have a lot of that brass left (AmmoDirect not currently reloading) and still use it for pistol loads. I do use Starline 45 Colt brass for my hot cowboy loads in my Marlin 94 rifle.