I have written a "commentary" on the problems involved with making repairs to these guns, primarily the Model 14 but it has yet to be published but having said that I thought I would just put out there some basic information on the functionality of the various parts and variations of same.
First of all, there are several variations of this part with bumps here, indentations there, ridges running the entire length, ridges running half way down, and totally smooth ones used mostly on really early guns or Model 14-1/2's. So when the little ear breaks off and you scramble to find a replacement your "quest" has just begun. The good news is that for M141 owners almost all of the A/B's are the one with the full length indentation but I have seen others.
I keep a drawer full of these things which is getting harder and harder to do because they are in short supply and like I said "one size doesn't fit all" but there is at least one major thing you can do to help yourself out. When you find a replacement or even if you are having binding problems with your existing cover, carefully open up the the A/B cover screw hole on the little flange. This must be done slowly and carefully so you don't bend the bejeebers out of the flange itself. After doing this make sure you file both sides of the flange smooth using a "needle file" or something similar. The enlarged opening will give you far greater versatility as you tighten down on the retaining screw, my practice is to thread it about half way, if there is no binding then give it a few more turns until the screw is tight and the A/B itself runs smoothly under it.
The other major thing is that a "burr" on the cover itself can bind the A/B up something fierce so before installing one make sure it is smooth on both sides and free of anything that could hang it up. It is also essential that you inspect the A/B itself, they get dinged, they also get clogged with 50-70 years of dried up glop so the channels need to be cleaned.
Owners of Model 14's in particular need to keep in mind that there were countless modifications and variations to all the parts, your chance of getting a replacement that perfectly matches is less than 50% in some cases far less than that as is the case with cartridge stops which is a subject for another day.
Bottom line is that if you go to replace your A/B cover, try to find one that resembles the broken one, keeping in mind that the impossible takes just a while longer but you will find it. If you are at this point thinking, heck when I need one I'll contact this "dude" he has a drawer full of them, please don't bother since I really need the quantity and variety to fix/repair the pieces that come to me for repair.
When and if I get in the mood again I will "attempt" to cover the cartridge stop variations but a tip in that regard is that most Model 14-1/2 stops interchange and the one offered by Wisner's (the 14-1/2 stop) has been a drop-in on four, maybe five guns I have repaired.......more later.....maybe!
OH! I ONLY work on Model 14's & 141's, I used to repair Type 14 Nambu pistols but the latter were apparently not made by Remington but sure have the same type of parts variations, these guns have become so expensive I gave it up.
Jim
Model 14 & 141 Action Bar Cover
Model 14 & 141 Action Bar Cover
Jim Peterson