Question - mag ext that uses existing cap?

[Carolinaflyguy]

Hi folks. Brand new to the forum and looking forward to it! I have an older 870 Express that has the magazine spring retainer and cap at the end of the mag tube - versus the dimples and corresponding spring retention device and cap. I am looking for a manufacturer of mag extension tubes that don't have the permanently enclosed front end but, instead, are threaded to accept the existing cap plus allow the insertion of the spring retainer. I've seen them but, for the life of me, can't find a name. Any help would be most appreciated.

[Synchronizor]

There are some extensions, like the Nordic Components kits, that use a separate screw-on end cap on their extension tubes.



However, I've never seen any that use actual 870 magazine caps. Even if they were made, I can't imagine it would be a good idea. Mag caps are designed to close off the end of the magazine tube, and secure the barrel to the receiver, so they're built way heavier than they need to be just to cap a tube.