I need a lttle bit more information in order to offer you the advice your searching for.
Are you loading 12 ga.?
Are they 2 3/4", 3" or 3 1/2" hulls?
What hull make, STS, AA, Nitro 27, Premier RXP, Gold Medal, Fiocchi, Gun Club, AA. The hull has some importance in refrence to the wad colum needed to provide the proper fit for powder and shot volum.
What shot weight are you loading, 1 1/2 oz., 1 5/8 oz. or other such as #12-00 buck?
I've been loading shotshells forever and will most likely have the information for you as soon as I get those details from you. I've got lots and lots of shotshell data and Blue Dot is a common powder for everything from 7/8 oz. up to 2 1/4 oz. loads so I should have no problem providing you with some help.
Here is one of the 00 buck loads using Blue Dot.
* 2 3/4" Federal Plastic Paper basewad hull, fold crimp
* 36.0 Grains Blue Dot
* Win. 209 primer
*Wad colum as follows-
1- WAA12R wad
12- 00 buck pellets
Estimated velocity 1261 fps
Estimatated PSI 9,800