To be completely fair to this class, I've seen a PO archery build pull off 7 ranged attacks by level 5.
Was a Barbarian/Ranger/Fighter tiny fey with a spike graft that added a ranged natural attack.
Took Two-Weapon Fighting, had Girallion Arms, Rapid Shot, Whirling Frenzy.
Had a couple flaws.

So 8 attacks at level 5 for this guy is just a smidge above what is possible for an optimized archer at current. But the True Archer doesn't GET 8 attacks at level 5, does he?

When I first read this, I didn't see Eagle Eye counting as BAB (Has that been changed?)
It seems to me from the wording that Eagle Eye is instead an untyped Bonus to attack rolls, you end up with a normal ammount of attacks at lv. 5 (2).
you immediately upgrade to 8 at level 6 because of Manyshot, which the optimized guy *Also* gets, which leaves Optimized Guy with more attacks; 2 from BAB, plus rapidshot, whirling frenzy, two weapon fighting, multishot, add his natural weapon, by the *Most Restrictive* interpretation of the rules, Optimized Guy gets 11 attacks to your 8. If TWF multiplies Rapidshot and Whirling Frenzy(Which I've seen arguments for), he's got 13. Both of you can use the same weapon enhancements.

So really, I'm not seeing how Volley Archer is overpowered, at all, before gaining the targetted AoE ability at level 15.
Even still, level 15 for a 3*3 radius attack is not out of line, especially when Wind Wall still renders the archer useless.

In fact, as far as I can see, the optimized little gremlin gets more attacks all the way up the tree. (He takes Fist Full of Arrows.) Given that the archer is limited to it's one attack method (Ranged attacks using arrows), I'd actually peg this class at tier 4.
With some decent magic items and practical optimization it might hit tier 3, but just barely, and since you don't get Use Magic Device as a skill, you'll be blowing a feat or multiclassing for it.

The Sniping Capstone is incredibly potent, but then again it's a 20 level class capstone.

Seems good, actually. I'd let this fly as currently shown.