When I made my tool for the spanner type ball screws, I used the needle bearing rollers from an old automotive universal joint for the pins. These compensating screws are usually very hard to move after being in place for well over 100 years. Tapping with a brass drift punch and long soaks with a good penetrating oil are highly recommended before even attempting to move the screw. The slotted type is easier to get loose without doing damage than the spanner type, and even they can be very hard to turn. A lot of people mangle both types by being impatient and using wrong tools and techniques. The ones I have removed have a very slight taper to the threads, and there seems to be a slight taper in the female threads in the action knuckle. Keith Kearcher said it was sometimes necessary to carefully polish the threads in order to get them to go in a bit deeper. Don't lose it, because they are a bastard size thread, and you don't see used replacements being sold very often.
As eightbore says, it is very rare to need to make adjustments using the compensating screw. Most of the time, the problem is not that the gun is off face, but rather wear in the bolt or the bolting surface on the rib extension. If this is the case, it is not that difficult to make a new bolt that is several thousandths thicker. The older pivot opener guns had a separate compensating screw just behind the dolls head rib extension to take up bolting wear. Incorrectly adjusting the compensating screw in the action knuckle can create other problems with engagement of the pin in the barrel lump and the cocking lever.
