Oh wow this maybe the fix. I’m noticing now, no matter how much I trim down or the necks. It’s not chambering. I’ll have to get a 300 saum caseI had a 7mmSAUM with a custom chamber. It was chambered specifically for Norma 300SAUM brass necked down. I tried factory ammo, 7mm Brass f/l sized, neck turned etc. It wasn’t until I measured the cases that I remembered the Norma 300 cases are slightly shorter. There was no way a standard 7SAUM was ever going to chamber without a ‘good’ trimming. Worth trying a 300 SAUM case necked down as a starter.