Dillon 550B sizing die question

[E53X5]

I just purchased a new 550B (my first press) and tried setting it up over the weekend, and I have a question about the sizing/decapping die. When I run a case through it, I can see the decapping pin raise about 1/8" (give or take) as it makes contact with the primer; then, it "snaps" back down and pops the primer out. When it happens, I can almost feel the vibration throughout the press as the pin snaps, and it feels as if the pin is hitting the bottom of the case first, then when I put some weight on the handle, the pin slides/snaps to the center and pops the primer out. I ran about 50 cases through it yesterday (9mm) and they all behaved the same way. At first I thought I had a bad die (with pin off center), but then I tried switching out to .40S&W to see what happens, and 9 out of 10 cases did the same thing (except the pin didn't raise as much as it did with 9mm, and didn't snap back down as violently), but on that other 1 out of 10 case it just pushed the primer out smoothly and quietly. My question is, is the decapping pin supposed to move up and down at all and snap like this, or should it simply push the primer out without much effort? If what I'm experiencing is not normal, and since both dies do more or less the same thing, I can assume the dies are not the problem. Could it be that my shell plate is off center? Anything else I should check?

Thanks,

Alex.

[High Lord Gomer]

In my limitted experience, I like it when it snaps because it has a beter chance of shedding the primer. I get the occasional primer that gets pushed out by the pin, holds onto the pin, then gets pulled slightly back into the primer pocket. My 9 & 40 don't snap and they have the problem with the primers not always getting pushed out and staying out. My 45 setup snaps and works every time.

[dillon]

This vertical movement in the decapping assembly is normal and intentional. If the primer requires greater effort to deprime, it compresses a coil spring on the shaft of the decapping assembly. This spring snaps the assembly down vigorously, to shake a stuck primer off. No worries

[E53X5]

Thanks for replies, guys! I'm glad it's doing what it's supposed to, because I was a little worried about breaking the pin.

[Braxton1]

About the only thing that I would consider doing is chamfering the decapping pin. Just chuck it in a drill and make the end round. The "square"-ish end on the decap pin will oftentimes hold the spent primer on the end of the pin and re-insert it into the pocket as the pin is being drawn back.

I've had this happen a lot, on both the old-style decapper and the new. It's a massive PITA on a 1050!!!

[E53X5]

I took a magnifying glass to my pin and it looks to be chamfered already, although it's still a bit rough. I'll have to remember your advise if I start having the "sticky primer" issues.