With the loss of original supply of 1928 and 1921 parts I make the checkered safety form bar stock. They are hardened and blued to mimic the original.
Thompson 1928 Checkered Safety
The Auto Ordnance Thompson 1927 A-1 can be converted to accept the FBI style removable butt stock as well as an additional bolt hold open switch to eliminate the “third hand” required when using a drum.
The dwindling supply of both smooth rockers and late style safety has forced me to make both. These are made from round stock and fully machined to duplicate the original GI and 1921 checkered styles.