what is this?

[mr2005]

what is this? (photo below)

took both my new mp55x and my mp15-22 out to fire last weekend. my buddy sees this fall off my gun onto the ground. I don't remember which gun i was shooting at the time but I have no idea what this is.

its rubber and has the sw logo inside. anyone know?

 

[BritDan]

It is the end cap off the stock tube on your 15-22 - as the 15-22 doesn't have or need a recoil assembly in the tube, they capped it off/made it a bit of a storage space.

 

[shovel99]

Have to chuckle at the thought....

.... of a part falling off one of my guns and not knowing where it came from. . I'll know where to come to get the answer!