I understand that it’s common to get soot on the neck of a case or even down the sides with a low pressure load or too thin necks, however I’ve never experienced it on the base of the case. It almost looks similar to a pierced primer, but the soot is easily removed and no marks on either brass nor bolt face. The brass is new virgin Lapua that has been neck turned to a loaded diameter of 0.288 to fit the .290 neck of my rifle. Using 107 TMK which are sat just below the boat tail, cannot engage the lands as the barrel is throated for 123-130gr bullets. Using Vihtavuori data, I started a ladder test. Both the first shots 38.5gr and 39gr showed the same soot. No pressure signs. In the picture it’s compared to a piece of brass shot on the same day but with 38.5gr of N150 and a 123 Scenar sat to touch the lands. The barrel has fired 20 rounds. I cannot understand why this is happening, I’m not using a low charge, all the brass is sized the same, all primed with GM205M primers. Any suggestions as to what’s causing it? Will it damage my barrel? Thanks, Josh.