Time your shots, and you can keep bosses like Phosgoth indefinitely staggered without running out of ammo. Requires a steady hand and nerves of steel, but on more than one occasion I've had PM's from randoms after clearing a strike, complimenting me on the final fight as a result. Truly skill-rewarding sniper. Absolutely love it.

^^ This... i see too many people spamming the ice breaker and then complaining they have to regen, if you time your shots, you should have a constant stream of ammo

And if you're hitting your precision shots, you shouldn't be taking any damage from the target at all, either. Just put the rest of your fireteam on the adds, and you're done.