[JFPNCM]

As a point of reference, I just checked a Musclechuck collet and it is 1 5/16” from the top rim to the bottom of the collet. Assume then that the shank should be inserted accordingly. To follow Stick’s suggestion that would be at least 1 3/8”.

 

[JFPNCM]

Not at all, study the photograph and you will see that only approx. the top 3/8" grips the bit close to 360° but to avoid run-out insert the bit 1".

Thanks Harry. Charles described that point earlier and I agree with both of you.