The en-bloc clip for the M1 Garand holds 8 rounds. I don’t know how this could be changed.
Well, the clip,with careful cutting/heating/bending can be made to hold a lesser amount -- even one round. I have an old American Rifleman magazine that shows how to build one for competition. But it depends on whether the clip is defined as a magazine. I suppose that's why the bill will be crafted to say seven rather than eight ---