The mysterious o-ring

[Intimid8tor]

Looking for some help from the bright group.

I was cleaning around my gun cleaning station and found an o-ring.

I will do my best to describe the o-ring and the firearms I have worked on/cleaned recently.

The o-ring is black which is the most common, but they do come in other colors.

O.D. .350
I.D. .220

Guns and accessories I have recently worked on and what kind of work I did.
M&P Pistols - field stripped.
M&P22 - field stripped and removed barrel nut which does have an o-ring, but it is bigger
HiPoint 995 9mm carbine - field stripped.
Gemtech outback ii disassembled.
Gemtech multimount - removed end cap.
DDLES 9mm lower unpackaged and looked at.
M&P15-22 disassembled and replaced trigger and hammer springs. (Is there an o-ring on the bolt?)
Cleaned 2 AR pattern rifles. Did not disassemble bolt.
Installed seekins rail.
Installed LPK including Norgin Ambi Catch. RRA 2 stage trigger.
Installed buffer tube,etc.
Removed and remounted Eotech, Aimpoint Comp M4
Mounted burris 3-9x50 scope and then dismounted.

Any ideas on where to look on the items listed.

[BigRich]

My $0.02 would be a suppressor end cap seal. Check to see if there is a groove on a male threaded section. That O-ring seems kind of small for that application.

[classwarfare]

Shoot, I thought this thread was about onion rings -- I like 'em.

My guess would be the screw on covers for the scope adjustment knobs.

[Redchevyman]

TAPCO vertical foregrips come with 2 o-rings loose inside the handle to use on spare CR123 batteries so they do not wobble when stored in the grip.

[Mickey D]

It's the firing mechanism for the High Point.

[Intimid8tor]

It's the firing mechanism for the High Point.

If I owned a VW Bug I would think it was an engine rebuild kit.

Thanks for the suggestions from everyone.

As an aside, the i.d. is slight smaller than a .22 slug.

[Toyman321]

my bullet button came with a few o-rings to be used as spacers

[8mmFMJ]

Rubber on a firearm? Hmmmm mine get realllly hot sometimes

[Intimid8tor]

Well, I think I figured it out. At least I hope I did. I don't have any exotic firearms and I talked to a smith about it as well.

I installed a Knoxx recoil reducing stock on a Mossberg 500 a while back. When knoxx sends those out, there is an o-ring on the bolt holding it in place while in the package. I looked at my package, where the original stock is, and the o-ring was not there so I am thinking that was it.