There are two types of irons, hosel and bore-through. Hosel clubs have a small metal joint linking the shaft to the club head, called the hosel. This is the club joint that is most often reshafted. Bore-through clubs don'tt have a hosel joint. The shaft passes all the way through the club head and can be seen at the bottom, or sole, of the club head. The majority of Callaway irons are bore-through irons, making the reshafting process slightly more difficult.
Put on protective gloves and leave them on for this entire procedure.
Heat the club head cavity, housing the tip of the shaft, with a heating gun. Dispense heat evenly throughout the area and don't be shocked about small amounts of smoke. This is just the old epoxy melting.
Pull the club head away from the shaft tip once all the old epoxy has melted. This should be an easy liberation. If it's not, continue heating the cavity because not all of the epoxy has melted. Don't twist the club head off or force it in any way.
Set the club head aside and allow it to cool completely.
Fit a shaft plug into the tip of the new shaft and roll a replacement ferrule (small rubber or metal ring that strengthens the bond between shaft and head) onto the tip. You can use the plug and ferrule from the old shaft if you want, but it's always a good idea to have a spare available.
Wind masking tape around the tip of the new shaft and use a black marker to draw a line indicating the correct tip angle. Use the old shaft as a guide to determine the correct angle.
Saw along the marker line with a hacksaw. Use short, forward-motion thrusts and reset in between each thrust to ensure a consistent cut.
Remove the tape and use sandpaper to smooth out the rough edges of the tip.
Clean out any remaining epoxy residue from the shaft cavity in the club head once it's completely cooled.
Drip epoxy into the cavity, along the inner walls.
Fit the club head onto the tip of the new shaft, not the other way around, and don't be surprised if small amounts of epoxy drip out onto the club head.
Allow the club to set for at least 24 hours before using. Also, sand away any epoxy that may have dripped out onto the club head after it has dried completely.
Specific golf shaft epoxy is available at most club fitting and golf outlet stores, however, any metal-grade epoxy found in a hardware store works just as well.
This is a messy and potentially dangerous procedure. Replace iron shafts in a garage or outside and exercise extreme caution. Incorrectly reshafting a club can cause bodily injury and/or ruin your club.