This is a good point to bring up.
Does the feeder work OK with some number of bullets but not others?
I use a collator with mine so the number/column height always stays the same.
For me, It was the tweaking/adjusting of the A collet for a firm grip on a bullet, to hold the weight of the bullets stacked in the tube.
For 9mm and 38/357 I use 3ft. tubes and put 50 bullets in each.
How it works as I see it.
The collet lengths are arranged so that there's an unclamp bullet between the A and B collet pinch points.
When the case opens collet A (and closes collet B) the bullet pinched in A drops into the case and the unclamped/middle bullet follows it into the pinch area of collet A.
When the case is lowered collet A closes around the bullet in it, and collet B opens allowing the column of bullets in the tube to drop down until the new middle bullet stops against the bullet pinched in collet A.
The pinch pressure of collet A is what keeps the bullet column from pushing the bullet out of it, so adjusting collet A to hold a bullet tighter will allow the use of the tube with a long column of bullets.
Sorry for the long explanation...
Pic of tubes lb. of powder for scale:
Top support for tubes:
Works for me,