1/2" UNEF BARREL THREAD ADAPTER (1/2”-28 UNEF TO PCO-1881)

A thread adapter to mount a plastic fizzy drink bottle with the usual ISBT PCO-1881 cap thread onto a 1/2”-28 UNEF thread (which is the most common .22" and 5.56 mm calibre barrel thread in the USA).

The assembly is intended to be used as a solvent trap/cleaning patch hog, allowing guns to be cleaned on one's kitchen table with lower risk of a rolling-pin or skillet injury :)

In any but the most totalitarian of jurisdictions, one could make a hole in the base of the bottle with a soldering iron and use it as an inexpensive disposable sound moderator (it gives about 10-14 dB sound reduction on a 22 LR rifle or pistol).

For a version which fits a 1/2”-20 UNF thread, search “PCO-1881”.

This STL download is free. If you find it useful please give it a "like" and if you would like to donate a few Satoshis, our Bitcoin Lightning address is: 0xd56cce09def24e8c@ln.tips
(Please note that this is a Lightning payment network address, not an email address).

Tested with PLA and CF Nylon.

Print threads-down, no support required.

For 1/28” pitch threads we use a 0.1 mm layer height, 1.2 mm wall thickness, 0.8 mm top and bottom thickness, 20% infill. This usually produces a thread which doesn’t need to be cleaned with a tap.

As with all muzzle devices, the thread should have just enough “play” to allow it to align on the shoulder. It should not be binding tight. If necessary, one can adjust print dimensions with Cura slicer settings.