930 SPX Barrel Spring?

[JoeII]

Please go easy on the new guy...
I bought a new 930 SPX and shot about 50 rounds through it, without a problem.
So, I decide to clean it and familiarize myself with it.
I field strip according to the YouTube videos and it's going fine. I noticed some fouling on the barrel lug that holds the Piston and decide to remove the slotted nut on the forward end...
Apparently a mistake was made. The spring in their packs a punch.
I did manage to get the area clean and put the spring back in. It was a challenge...
My issue is, I have a a part that I can't identify and don't know where it goes.
It is a tapered ring, about the same size as the Piston rings, but without the split. I have attached a couple pictures of the part. One side is flat and the other is tapered. There is also a groove inside. I found some parts breakdowns on line, but nothing definitive.
1. What is the purpose of this ring?
2. Where does it go?
3. What is the orientation of the tapered side?
4. Also, what does the spring do?

Thanks for your help,
Joe

 

[John A.]

Is it part #25 on this schematic? Mag spring cap?

https://www.mossberg.com/schematic/?model=930-12-gauge-shotgun-schematic

 

[JoeII]

Is it part #25 on this schematic? Mag spring cap?

https://www.mossberg.com/schematic/?model=930-12-gauge-shotgun-schematic

Don't think so. I don't see the part on the drawing.

 

[John A.]

I don't know either then.

You could call Mossberg and ask them. Maybe they would know, but they probably have the same information about it as you do.

 

[JoeII]

I sent the same info to Mossberg support. We'll see what they say.
Kind of surprised no one I here has any input.

 

[JoeII]

Update from Mossberg -
The part is a gas check ring that goes inside the barrel lug in front of the gas piston. Tapered side towards the muzzle.
I'm glad it doesn't go next to the nasty spring...