Depends on your drill.
Bourgualt recommends pack master be set for 180 to 220 on a QDA drill on average.
XTC drill 190 to 230 on average.
You can go higher or lower than that, but those are the numbers I was told by BG for a general average.
Always calibrate your pack master every season with a block under the opener so it does not hit the ground.
I have an XTC drill and have found that 190 is definitely at the bottom end of packing. The packing pressure is enough, but the openers are not quite firm enough to stay steady in the ground and seed depth will not be quite as exact as I like. Ground truth seed measuring will determine this. Move up to 200 and you get more precise depth and consistent depth.
We are in the brown soil zone, so these settings may be different for your conditions.
I keep notes on my phone during seeding on pack master settings for different soil conditions. One note I have for 230 pack master setting on the XTC drill is "it's a firm effiin pack". I use that setting only when it's getting stupid dry.
I really like pack master and would not run without it.