As a sniper you can get the Snap Shot skill in the Marskmanship tree:

- Level 1: Entering cover has a 50% chance of making the next Snipe activate instantly. This effect cannot occur more than once every 6 seconds.

- Level 2: Entering cover has a 50% chance of making the next Snipe activate instantly. This effect cannot occur more than once every 6 seconds.

As the skill describes getting into any cover will grant you a 50/50 or a definate instant snipe depending on your level in it, however from personal experience this is false.

When entering your deployable cover and having the skill at level 2 there is indeed a 100% chance of instant snipe, but using hard cover (rocks, terrain, etc.) there is still only a 50% chance at level 2.

Workaround: Don't have anything targeted when you enter cover, that will make you enter cover where you stand (deployable cover) rather than roll to the nearest pebble.

Sadly, this bug has been around since release, and they don't seem terribly inclined to address it since there is a workaround.

Workarounds = cheaper than fixing issues.