If you are having problems with the primer sled moving up under the shell plate all the way or hanging up resulting in some missing primers, or primers not quite being seated, check the nut under the ram /shell plate base that holds the seating rod /primer punch in.If its screwed in too far that will cause hangups and missing primers, it may need to be backed out a little.
I disagree with that suggestion ... it has to be screwed in all the way and the only way that could be an issue is if the punch itself was too tall. That would have two effects:
1. prevent the slide from sliding back as the primer punch would hang in the empty primer hole instead of letting it pass over. You'd feel the resistance as the plate tried to turn without the slide backing out.
2. When the slide returns to the punch hole, it would stick against the "too tall" punch. You'd be looking at a slide with a primer in the carrier that couldn't reach the punch position.
The only way to have those issues is if there's a grain of powder down in the punch body or the punch itself is physically oversized (pretty unlikely but I guess not impossible). Anyway, it's easy to check when installing the punch - the slide should move on and off the punch position within a few degrees of plate rotation. If the punch frequently grazes the slide (ie. the punch is high enough to feel) the more the underside of the front lip will wear down - - I replaced the LP slide around 30k rounds as the front lip was down to about a hair of metal left...still worked but wouldn't have lasted too much longer. If too tall is a persistent issue, use a thin paper or cardboard shim between the underside nut and the plate - don't simply loosen it as it will loosen further with press vibration and you'll get ...
primers standing proud of the case primer pockets and, when a primer is sticking out enough, it'll arrest the plate rotation completely.
Geez, kind of wordy ... anyway main OP issue is the slide picking up a primer - nothing to do with the punch end of the set-up or the underside bolt.
The high primers when they do feed could be junk in the underside bolt case that keeps the punch from fully extending upward, or a loose nut securing the punch.
/B