Some of the TC aftermarket barrel shops marketed their own "on-off" brake systems that include a plain cap (VVCG, MGM, Steve Stratton, Bullberry, etc), others their own brakes without caps (Bullberry, SSK, etc), plus most of them also install brakes made by other MFG's same as could have been done by any gunsmith/machinist. Only fly in the soup is not knowing who made yours means not knowing for sure what material yours is made from. But with the specs in hand for the cap you need any of them, any smith or machinist could make you a cap. Simply measure what you have/need or send them the brake to measuer themselves and try to match materials.
It's been a lot of years since I saw one in person, but if I had to guess from the picture it might be a Stratton made brake (Steve Stratton himself still does them I believe, or it might be from when he and his son's worked at VVCG or if more recently by his son's at MGM where they are now).
Match Grade Machine (MGM) is in St. George, UT
Steve Statton's Customs is in Hurricane, UT (and so is Bullberry).
