Umm Luck haha... Strike play list is the best way to get them... That is only of coarse if they're not being sold by the gunsmith in the tower. So keep an eye on the gunsmith, it's the easiest way. Save up your glimmer because it'll cost you 1600 a piece. But if you play like it's your religion like my clan, money isn't ever an issue. And yes LUCK does actually help! cause EAL Courtesy of (Engrams Aint Loyal)