If the bullets are not stable you will know it the first time you punch paper with it, the bullet will go through sideways. If they are going straight through the paper then they are stable, just because they don't shoot well does not mean they are not stable, plenty of light bullets don't shoot well either. I cannot imagine that a 9 twist won't keep a 70gr bullet stable unless it is a long pointy nosed boat tail bullet. Your best accuracy will be when the bullet is just a little over being stable, so too much twist is bad. This is especially true at long range, an over stabalized bullet ends up flying nose up way down range, so the BC of the bullet is much worse than what is published. Just load some up and shoot them and see what you get. Larry