Barrel ID for SL 68 II?

[C26G]

Wondering if anyone has seen this style barrel before? Old Tipmmann SL 68 II. Looks like carbon fiber and has a slightly rough texture to the outside, smooth as glass inside the bore. It's been called ceramic, and couple people said it's an old J&J Barrel. Any info appreciated - thank you

[DocsMachine]

That's a factory carbon fiber barrel to an old TM-11A pump.

Doc.

[C26G]

Thank you - appreciate it!

[Ecapnation]

Bingo

[Chemical-x.....ahain]

can TMs be made to function after the nylon bolt catch has been worn away? id assume a new catch, do they need to be nylon?