looking at the Reddit thread you have a 6% drop rate (Destiny)

by Durandal, Tuesday, March 01, 2016, 13:39 (3028 days ago) @ Schedonnardus

3% on Rocket launchers, 5% on the sniper rifle.

Given all the other variables in perk and light level, there needs to be a big increase in the drop rate. If you grind strikes with 3 of coins, you could expect two exotics in an hour, where as 4 IB matches might get you a single drop. I know I got a Sniper drop but sharded it because both the light level was low and the perks were not more compelling then my other sniper rifles. Same thing with the arms I got.