Patches are compressible and will fit well enough to stay. The wads behind which take up excess space in the shot shell keep pushing the patched ball ahead of them and since the patch is already around the ball, it stays. The boys here, as I said, have been doing this since the early 80's and they were shooting .684" balls with about .012" patches through a .690" choke - no damage - BUT - do be careful about shooting oversized combinations - don't know how strong or resistant your gun's chokes are.