Dear Tracie, please find enclosed a couple of photo's of the act" fort-grip used by the British Amy to test the best position for the sling swivel. Ile screws used to retain it are shortened slightly so that they presumably don't protrude through the other side. Full length screw as used on rifle shown on left of shortened screws

The retaining bolt was tight inside when it was given to me by CSMI Doug Maber, one of those instructors doing the trials on the first Thompsons in 1940. When I looked at it, it looks as though it's been lengthened slightly and brazed together. I cannot see why but an original one is shown (left) alongside it. There is just sufficient thread to screw into the grip rail.

You might notice that the ASSEMBLED photo shows a No4 rifle sling swivel fitted. This is because the offset loop type No1 rifle swivel was quite rusty and I assembled a No4 type just for the photo. An original Not type is now fitted.

Nobody seems to know why there is a hole in the center of the recess. Doug Maber said that he believes that it might be that another type of sling, probably from the Bren butt was originally fitted.  It could possibly be the correct explanation because the top of the grip has been heavily patched.  A patch line is clear across the bottom of ft recess (see my sketch)

Hope this historic info is of interest. Peter Laidler