Re: Slotting the feed ramp on a SA
NOTE - The following is not to be construed as any instruction, and any action taken based on the below is at your own risk.
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There's no real advantage in modifying the action unless you have a magazine that gives you the ability to load longer - examples of these are modified AICS with the spacer plate removed, or the Alpha magazines designed to work without a spacer plate.
In either case, once you start to run one of these style magazines there's a good chance you'll end up with a witness mark on the bottom of the action where the front edge of the magazine rests. I just used a dremel to open the action the edge of that witness mark, then blended the feed ramp to that point. Go slow and it'll work out fine.