David Rase's is the best I've seen or used.
Jeff
Anything you get from Rase is first class!!
You'll notice he hasn't responded yet....
That is because I don't have any for sale and don't want to make any more at this time. I may make another batch later this year. If you would like to build one on your own, here is how I make them.
The backbone for this jig is a 5/8" piece of solid square stock 12" long. I measured all the guards I had on hand and none were longer than 11". Next I made a couple of arms 5" long out of 3/8" x 1 1/4" flat bar. There is a 33/64" hole on one end of each bar and a 3/8" hole on the other. These are bolted to the 5/8" piece of square stock. The two 1/2" diameter rods are 4" long and 5" long. They each have been split for 1 1/4" down the length to accommodate clamping of the triggerguard tenons. I used 6-32 socket head cap screws to draw the cutoff pieces of the rod together.
As you can see, the triggerguard is free to rotate 360 degrees with no interferences. If the piece is too high in your vise you can loosen the 3/8" bolts and lower the arms to obtain a more comfortable filing position.
David