I haven't posted about this until now because I figured someone already figured it out. I typically just use this site to see what others are saying about the easter eggs but there was never a reason for me to make an account because it didn't require one to read topics which is why this account is brand new. There is definitely a steady aim "permanent perk" or "persistent upgrade" I discovered it with the HAMR while the running a rape train in the m16 tunnel only hip firing till around round 20. Similar to the other non purchaseable perks you will receive a green puff of smoke when you achieve it. The crosshairs will become noticeably smaller. I believe you can level this perk up several times because I received multiple green puffs throughout my game to the point whee the the Cross hairs were as small as that of and smg with laser sight laying prone. I will get this upgrade again this weekend and post a before and after picture to prove it. If anyone makes a video of this perk all I ask for is a shout out.