Slippery End Mills

I have previously discussed the problem of 1/8" end mills not having a flat spot to lock them in end mill holders.  I focused on how vibration made them work loose, causing the end mill to fall out after last cutting pass.  Today's discovery is that if trying to cut vertically at too high a speed can cause it to retract back into the holder.  This means the 0.4" deep cut turns into about 0.2" actual depth.