Bloodborne's patch 1.04 made Blood Stone Chunks available in the insight store for 30 insight, but gathering that much can take a while.

Luckily, thanks to the changes to chalice dungeons boss drops, there is an ever better way to get the chunks that will let you upgrade your weapons to +9.

The only requisite is being able to access a cursed Isz chalice dungeon.

Reddit user VoidInsanity discovered one in which the Bloodsucker boss right on the first level normally drops two chunks (with rare cases in which it drops one or zero), plus a weapon gem. The dungeon's glyph is "jemmjmpi."

• Use jemmjmpi
• Kill Brainsucker boss and reset
• Brainsucker boss drops chunks and a gem. Normally drops 2 chunks, very rarely drops 1 or zero.

User techrogue posted a handy checklist on how to do it as fast as possible.

• Drop down into the pit
• Take the tunnel that doesn't have a witch's summon lurking in it
• Don't pick up the shiny, there's a teleport trap in front of it
• The only path forward leads to the lever and a brainsucker
• Go get rekt by the boss because the magic spam is real

After doing that (possibly avoiding getting "rekt," but if you can access the dungeon you should have no problem), you'll just have to reset the dungeon, following user joseangelhe's handy insptructions, in order to do it again.

• Create the dungeon.
• Kill the boss.
• Return to the dream and remove the chalice you just created
• Create the dungeon again.
• Rinse and repeat

Finally, if you want to get a good idea of the route, you can check out the video made by user treesandgames. It takes him only two minutes and 25 seconds, which is definitely quite sweet for two chunks.