I ran across this in one of the gun groups I belong to. Owner drove 400 miles to get this Unertl Target/ Programmer and mounted it on his BSA MK III small bore match rifle. These are amazing rifle capable of astounding accuracy with proper match rimfire ammo. I once saw Brady use his to put a shot through a life saver hard candy without breaking it at 30 yards. His had an Eric Johnson 5 star barrel on it. I have no idea about the gun pictured.
The weird looking thing on the bottom of mid forearm is for standing offhand shooting. You place it in your left hand palm and it helps with proper offhand technique. In front of it is the hand stop for prone shooting with sling