There are a few flaws in his list, an example, the Schmidt P8126,7, and now the P8120 have a thicker barrel than the Parker style refill, and will not fit in some barrels, and the tip is a little thicker and will not fit through some nose cones.
In fairness Richard, he does state that he hasn't tried every possible combination and that errors are bound to be there. But he also asks that if anyone comes across any, then to please let him know, so he can update.
I assume that in the interests of pen making, you have told him?:wink: