I was shooting my 20g for the first time (got it used) i took a shot, pumped a new round in but before i could pull the trigger again i had to cycle the safety.
Is this the design or do i need to replace the safety parts? I have not had to this with other pump actions. If it is by design can i replace it with a new selector kit and alleviate the problem?

Definitely not design but don't know how to fix it.

My 500 does the same thing. The tang safety is loose and a hard pump will knock it back into the safe position.

It should have a very simple tang safety. Take the barrel off. Pull out the trigger group and then the bolt carrier and the bolt. This will expose the underside of the tang safety. Tighten the screw on it. If it's an older 500 tighten the screw from the top of the tang safety (no disassembly required).

I took the screw out (allen head) the slide plate under the selector looked a little worn, i flipped it over, tightened the screw up pretty good, then i cycled the pump a few times and watched the selector work it's way into the safety position. I sent an email to Mossberg, waiting on a response. A couple of buddies keep telling me to do away with it all together, i don't care for that idea but come September i don't want to be missing birds.

Let us know what the solution is, Mike. My sons will do the same thing except his safety is too tight. He is 12 and able to work the safety but its not easy.

Will do.
i got my safety really tight and it is hard to operate. We shot skeet Friday afternoon and it was pretty frustrating. Between that and having the full choke for turkey still in it, i barely hit half of my clays.

Mossberg wants me to send it in, 30-45 day turnaround

I opted not to send it in and just ordered the parts. I had a metal thumb selector and a hex head screw already on it so, i re-used those and replaced the spring, the bb and the thin plate that it's under the thumb selector. This seems to have fixed the problem, i have not shot it yet but all i had to do was rack the slide a few times to get it to move and it did not move after i replaced the parts. This was a $15 dollar fix, if i didn't already have the metal thumb selector it would have cost about $25.

Interesting. My sons 500 was disassembled the other day for the preseason clean. Will order the parts tomorrow.

Thanks for following up on you post sir.

fired 3 rounds out back today, no issues, it works fine.