If you ever need to know exactly what to add, it's not too bad to figure out.
Measure the exact length of a shaft or a piece of a shaft, round numbers are easiest. Let's say we have a scrap that measures 10", end to end.
Taper one end and put on a tip, you don't need to glue it but it should be well seated just as if you were glueing it.
Now measure from the back of the point to the other end of the shaft. Let's say this one now measures 9 1/4". The difference is 3/4", that's how much extra needs to be added for that particular brand/style/model tip.
Guy