Pete B in Wisconsin

I have a West Hurley AO 1927A3 with the stick mag adapter. The problem is that I also have drum mags and need to know how to remove the adapter. I have searched online without any luck. It appears to be nothing more than releasing the magazine catch and sliding it out the side. Although loose I can't get any movement and am hesitant to use a screwdriver for fear of damaging it. I am probably missing something obvious but I don't have a frame of reference for doing it correctly. Any help is appreciated!

I just purchased an older .22 conversion kit for a .45 Thompson. Unknown manufacturer it comes with one magazine. The length of the barrel liner wold indicate that it is most likely for a FA SMG but I cannot document it. Is anyone familiar with this item that could provide me information about its background? Also looking to sell it if anyone is interested please contact me direct: pbrierton@att.net<_< **Sorry attempted to upload pics several times, system wold not let me, contact me directly for them.