Bkhamlin;
I use a set of ski vises. Mine happen to be the Swix brand, but Toko would work just as well. If you live in ski country they're easy enough to pick up at a swap or garage sale.
The great advantage to them is that they come with rubber padded jaws and since it's a set, adjusting for various length guns is a snap. They really are a very nice accessory to any tool bench whether or not you ski, or shoot, or not.
900F