ATF approval letter was sent to us. We will not provide the entire verbiage from the ATF letter because it contains proprietary information; however below is the important part:
“…To complete the present evaluation, FTB installed your kit into an open-bolt, “semi-auto” MAC-10 type firearm and test fired it. The kit did not defeat the semi-auto trip and did not cause automatic fire in the SEMI selector position. Therefore, we find that the submitted .22LR caliber conversion kit for MAC-10 type, open-bolt firearms is not regulated under the GCA or the NFA.”
This is great news for the entire MAC world!