Carbon steel shafts are extremely hard and require a special carbide drill bit. This kind of bit is expensive, somewhat hard to find, and very brittle. It can be used with the jig but you must be very careful and keep the jig/shaft well aligned directly under the drill press so as not to stress the bit sideways, otherwise it may break inside the jig.
Like I said drilling a carbon steel shaft for flopper hole is pointless as the hole will rust and then the flopper will no longer move smoothly. A rusty hole for your application may not matter, I don't know. Speardiver carbon steel shafts are in the works, I may add that extra hole. What is the exact position you want it? 1" ahead of the forward most loading notch?

