Ok, so after doing some hunting, here's what I found:
That seems to be the basic guide on how to Charm Snipe, although reasoning isn't provided.
For those that want some step-by-step instructions:
Generally, it seems that the RNG isn't so random, but rather cycles through a pre-generated list. "Actions" use up these random values. What defines an action is still up in the air, but even just standing around doing nothing uses them up.
Another thing to note is that charms gain their skills on appraisal, I believe. It may be possible to test that, and I shall. They key point is that they are not gained upon mining it.
- For best results, you need to be at least HR8 online. You can do this in Misty Peaks at HR3, but your mileage may vary. The link doesn't address High Rank, but I suspect some charms are only available through Timeworn or Enduring charms, not Mystery or Shining. Will test to confirm.
- Wear the Leather set. Presumably for the Gathering, Whim, and Speed Gathering skills.
- Gem in Bombardier. Mostly for your suiciding efficiency; spending time uses up actions, and you don't want that if you're close to the charm you want.
- Dump everything out of your bag. Put three Large Barrel Bombs in the first inventory slot, and two Large Barrel Bomb+ in the second slot. I don't think this counts as an action, but is more for suicide efficiency.
- Bring along some Pickaxes. Y'know, so you can mine.
- Punt Cha-cha and Kayamba. They'll spend actions you don't want.
Save game prep
So, now that you've finished preparing, you need to figure out where you are in your RNGs. You do this by performing one run as fast as you can. The charms you get can be cross referenced against Athena's Charm Table. Find your charm in the correct table and right-click it; the RNG value will tell you where in the table you are.
Obviously, you need to know what the RNG value of the charm you're after is; Athena's Charm Table is perfect for that.
- Load your savegame.
- Grab any non-Harvest Tour quest for the Misty Peaks (theoretically, any area would work, I believe).
- Eat for your Explorer skill that you've locked. If the ingredients aren't Fresh, use a Voucher.
- As soon as the quest starts, mine out the hidden area, and gather if there are bones.
- Drop a Large Barrel Bomb, and kick it. It will explode.
- Repeat step 5 until dead.
- After you've carted, sprint to Area 1, and drop a Large Barrel Bomb+. Kick it. It should kill you.
- Kill yourself again with Step 7.
- Congratulations, you've failed the quest. Your consolation is the charms you just mined.
- The Appraisal screen will give you your charms.
- If you didn't get your desired charm, re-load. Otherwise, congratulations! You just sniped your charm.
Now, the idea is that once you figure out where on the RNG you are, you want to figure out how far away you are from your chosen charm. If you want, say a charm with RNG 5000, and you find out that your charms give you RNGs of 4000-4500, then what you need to do is delay your third death for a bit. Exactly how long is up in the air, and hasn't been completely determined. Some testing has shown that it's roughly 300 "Actions" per minute of waiting in Area 1 of Misty Peaks. So that's about 5/second. What you can do is keep track of the quest timer, and note the RNG range of the charms you got. If the one you want is inside that range, you've found your time limit.
If you're really far from your desired RNG, you can waste some Actions by just going to Moga Woods on a freehunt, and just stand around for a bit. Save right after, and you've permanently moved your RNG forward a bit. Note that it wraps around back to 0 somewhere around ~5400.
Once you've found the correct time range, you just have to hope that you get your desired charm. If you don't, reload and re-run, and try to kill yourself the third time at the same point in time.