My first post and I'm jumping in with both feet.
I have used this vise, or variations of it, for three builds now and it works well for me. I have used the conventional modified machinist vises with supports also, but prefer the rigidity of the two point clamping this vise provides. I have used 6 inch trigger clamps that are modified with slide on swivel pads that I made on a mini mill. Using four swivel pads is a bit of overkill. The clamps are rated at 300 pounds clamping force and are one hand operation. You can probably figure out the brand by the color. The clamps work OK without swivel pads because the uprights holding the clamps swivel and slide to accommodate variations in the stock. The clamps are adjustable up and down mainly to accommodate holding a barrel for draw filing and finishing. Not counting the swivel pads there is less than $75.00 spent. The T-track, which holds 3/8 bolts, and clamps being the bulk of the cost. I routed coves into the base for part and tool resting places. The whole vise clamps to my workbench.
I have measured drawings (1:1) if any one would be interested. They were done in Visio which I can convert to many different file formats, which I cannot guarantee, though .pdf seems quite good and can print actual size on standard printer paper. I do not have drawings of the swivel pads available.
I am currently working on a test of HDPE (high density polyethylene) swivel pads. Much faster/easier to machine and I suspect strong enough. I'll see. I've changed the pad design to beef up critical areas.