Sure Shot

Name: Sure Shot
Type of Rune: Hand
Type of Casting: Harmonious
Appearance: A single black arrow on the back of the hand, from the wrist to the bottom of the middle finger, this rune looks exceptionally mundane before activation. When activated, however, it seems to expand and become darker, like a vacuum breathing in the essence of the world.

Effect: As the rune seems to suck in the essence of the world, the user's hand begins to feel exceptionally full of energy. This seems to calm the hand, removing even the slightest quiver, but brings with it intense pain. For the next ranged weapon (projectile or otherwise) used, the user can realize a potential s/he didn't even know s/he had. The weapon flies with unerring accuracy toward the target at 50 ft/s faster than it normally would, up to 100 feet farther than it normally would (for arrows and bolts) or 30 feet farther than it normally it would (for thrown projectiles, excluding missiles from a sling, which can go up to 50 feet farther), and slowing at half the rate it normally would (e.g.an arrow shot from a longbow would travel 250 ft/s, slowing at a rate of 25 ft/s (minimum speed remains unchanged, so, for this instance, 50 ft/s), up to a maximum distance of 1000 ft). The missile also deals 60 additional damage upon a successful strike. Once the missile has been released, the energy bursts back out of the user's hand, dealing 40 damage to him/her. This rune can be activated almost instantaneously, allowing for activation and the firing of the missile in the same post without a chance of being interrupted between the two.

Action Cost: 80
Memory Slots: 5

Patience Required: 50
Word Count to learn: 700
Word Count to Inscribe: 500

So, you mentioned any projectile. Perhaps lower the range this extends by for thrown weapons? As a throwing knife can be thrown 60 feet by a normal person, but 160 feet would be insane.
Perhaps also change a little bit about this, not sure what, it currently it is fairly similar to the ranger sharp shooter skill. I think it is different enough to be approved, but if you can think of a way to change it enough, that would be nice, but completely up to you.
Aside from that, all looks good.

Lowered projectile to 30 feet except sling stones, which are at 50. The goal was to provide some way for other classes to emulate the ranger's exceptional proficiency without having to multiclass. It has its ups and downs compared to the ranger skill, but is a boon for anyone, including rangers, so the goal was to provide something roughly similar to other classes at a price. I could try to make it a bit more different if such is deemed necessary though.

Naw, just an idea. Looks good to me. Approved.