I have a fixed Magpul rifle stock. On the end that goes toward the receiver, there is a rectangular nub. Colt recommends a certain gasket that go around that to prevent a possible rattle.
I bought some before from that one Colt OEM parts place that I think is no longer in business.
What is the name of this gasket and where can I get more?
Is it possible for you to measure the nub and the slot it inserts into?
Let’s just say as an example the nub measures in mm 5x5x5x5 and the slot is 8x8x8x8. That would mean the o-ring needs to be 1.5mm width ( diameter of thickness ) or 3mm/2 ( diff. in nub to slot )
They are sold by OD x ID x Width/Diameter Like say 10 x 7 x 1.5. You could then estimate that your 5 x 5 x 5 x 5 nub = 20 ID if square so maybe an 18 ID would work or even a 16. The o-ring is going to stretch easily. The width or gap it has to fill is going to be the critical part. Tons on ebay. Assortments or specific sizes. The black rings seem to be the most stretchy. The green ones not so much. You probably want the stretchy ones.