Ahhh... now it's making sense.
When making a full tang knife, or a folder, the bolsters are applied much like a sandwich - and a 1/8+ bar is ideal to cut the pieces out ofand apply them.
If you are sliding "stacking" layers over your hidden tang, you may well want something thinner - and I have not seen 416 offered that thin. If you want to slide a guard over the tang, you may want even thicker than 1/4.
At any rate, if you can picture a piece of bar stock, maybe 1/8 to 3/8 thick and 1 to 1 1/2 wide and usually about a foot long, it's not hard to hacksaw off the piece you want and start shaping it.
One thing to keep in mind is pins if you are using them. Your pinstock should be the same steel as the stock you are pinning.
Rob!