I can't comment on the C model, but on the B model having the primer slide jam is very rare.

When it does happen, it's the result of grit getting under the slide or under the plate below the slide, or it's the result of a serious mis-alignment issue.

When I swap from large to small primer slides, or vice versa, I just leave the screws under the primer assembly slightly loose until I lower the shell plate over the primer cup. With the shell plate in the lowered position I then snug up the screws with an allen wrench with finger pressure on the short arm to "torque" it.

Mine never needed any filing, nor did it require loose screws. In terms of cleaning I brush the whole area clean when ever I change shell plates or switch primer slights with a small brush, like the small paint brushes I use to remove swarf on my lathe - just without cutting oil on them.

There are third party primer slides available that use a roller bearing that are probably less likely to jam due to dirt, but I've never seen it as a large enough problem to bother getting one.

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I've owned my 550B for about 20 years and it's seen between 10,000 and 20,000 rounds per year.

The only issues I have had are:

- a screw under the tray that feeds the shell plate periodically loosening so that it would not allow the shell plate to go all the way down, resulting in high primers (it was hard to diagnose the first time it happens, the other two times I knew exactly where to start);
- the plastic cracking on the clamp for primer alarm (which was no big deal as I never found it to be useful - you can feel when you don't seat a primer and the visual indicator from the follower is plenty of warning, no audible warning is needed);
- dirt, or a spent primer falling in front of it, interfering with the primer slide; and
- the cotter pin that serves as a hinge for the spent primer chute getting bent and preventing the chute from pivoting(you'll find better replacements in the form of a small nail, a 4-40 bolt, or even a heavy duty paperclip).