I recently purchased a custom 330 Dakota and it came with some commercially handloaded ammo and some NIB brass. The custom ammo is from Superior Ammunition and is loaded with A-Square brass. The NIB brass is from Dakota, but comes with a sticker saying it is Mast brass.
The original owner of the gun used A-Square brass for his handloads and reported being able to use powder charges that were considered hot by his reloading manuals. I loaded up some rounds using the Mast brass and got sticky bolt lift below max loads according to Barnes #3. My pressure testing loads were 210 grain TSXs over 70, 70.5, 71, 71.5, and 72 grains of Varget.
The sticky bolt lift came at any charge over 70.5. I thought this was unusual because I've never had any problems working up loads to max charges using TSX bullets in all of my other guns. In fact, some charges in my other guns went over max loads (based on Barnes advice that TSX bullets could handle 1 or 2 more grains of powder over regular X bullets) with no signs of pressure. Does the Mast brass have less case capacity than the A-Square? All of the A-Square brass is loaded so I can't compare volume or weight.
To complicate things further, Mast is out of business and Dakota brass is now made by another company. Maybe Norma if some internet forums are correct? I only have 20 of the Mast brass and 20 of the loaded ammo with A-Square brass. I like to have 100 brass plus a few spares for the calibers I load for. Anyone have any idea how the new stuff compares to A-Square and Mast brass?