Marskmanship = 2x Sling Quality
Perception = Enough to try and max your damage.
Minimum damage formula = (0.5 ( PER/AGI) * MAX-DAMAGE)
Your perception, enemy's AGI.
Base damage is 60 for a sling.
Quality scales regularly: base * sqrt(q/10)
Assuming you can hunt bears and with decent survival to get at least a q100 sling...
Max damage: 189
Max Marksmanship you can get a bonus at: 200
There's really no point in going past 150 Marksmanship for a while if you only want to use a sling. You'll want to use a Bow/Ranger's Bow if you're hunting anthing above animals (that is, hunting humans).
Keep in mind that even a q80 Ranger's Bow (would be pretty friggin' tough to make) wouldn't be able to do much to someone in full q80 bronze armor.
(q80 Ranger's Bow is 848 damage, adding q150 Bone Arrows is another 77 damage)
If you're intent is safety or hunting of other players you should probably roll something other than marksmanship unless you got melee people to back you up

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If you want to raise your sling Q you have a few options:
1)Something worth selling, or can get to nople and pump out bricks? Trade for a nice quality sling.
2)Want to continue raising the quality to continually use slings? Keep making hemp and raising the string Q

3)Want some fast way to do it? Kill a bear, dry hide, hide straps.
3)Near a high quality soil spot? Grab nettle/taproot until you have 5, make sling.
You'll need some survival either way so the bear one is probably the fastest.
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