Gave my 20ga a good cleaning for the first time in years. Used an air compressor to blow out the unfired powder flakes. After re-assembly I dry fired with a snap cap and the bolt would not pull back. only thing I can see is that one empty hole that would be a pin right under the coil spring. the Numrich website parts diagram is impossible to read. Any idea on the specific name of this pin or do I just order all of them and have spares?

How do you lose parts while soaking them in a pan of solvent? Even if they were to slip out while handling them, they should be in the pan or on your work bench. Hopefully you didn't blast it with an air compressor while in your grassy back yard.

I've never understood the practice of blasting an assembly of small parts, pins, and springs with an air compressor unless you're running an assembly line where time is money. What's wrong with just cleaning them with solvent and then letting them drain dry while lying on a paper towel on your work bench?

I just looked at mine. That pin, through the trigger, has just the hole on the left side of the gun to escape from... there is no hole clear through the other side on my 20ga. 48AL. That's some really bad luck if you did lose that one. It's flush with the left side of the trigger and hard to see... are you sure it's not there?