On taking apart a 1947 Ideal Grade I noticed it has a bushing that is between the two side plates. It also had one that went from the top tang to the trigger plate housing. This gun also has a Hunter One Trigger, and I am wondering if this is just on some of the later production grades that have the Hunter One Trigger.
My theory is so that you cannot over-tighten the these two screws and bind the HOT.
I have only seen this on one other gun, that also had a HOT.
Let me know if your gun has this and if it does have a HOT ir does not.
Since these guns at the time had a life time warranty, I feel that they were put there because as now, too many guns were taken apart with the HOT and now weren't working.
Just a man hour cost saving feature that could be eliminated.
I also noticed in this gun, that the top tang area did not have to be milled out for the second firing of the HOT. I did take this measurement and from the top of the spur lever in the safe position, resting on the spur block, it was 1.290 to the bottom outside of the trigger plate housing. I do not have an earlier one taken apart with the cut-out area to measure right now. Naturally this is only on FW framed guns.