Mossberg 4x4 extra part?

[willymc]

My next door neighbor and one of his friends just bought Mossberg 4x4s. One in 30-06 and one in 7mm rem. magnum. In both boxes was a small black tube about 3/4" long. They are knurled on the outside and threaded on the inside. They both appear to be the same size. My neighbor asked me if I knew what they were and what they are for. I said I had no idea but I'm sure someone at THR would be able to help. So, please help!

 

[ugaarguy]

It's a thread protector. If you remove the muzzle brake you use that part to protect the threads on the barrel.

 

[willymc]

Thanks for the reply. That makes sense.