It depends on the gauge. The 12 gauge has the notch in the receiver. But the 20 does not because the pin in the smaller bolt clears the edge of the port without a notch. The same is true of the Belgian guns. I don't recall whether the 16 gauge has the notch or not; maybe someone else can help on that one.
Edited to add:
I am both amazed and amused by the "wild blue yonder" ideas that can arise from a simple and obvious engineering change. How did the idea arise that the Remington guns were not meant to be disassembled or that there was some kind of "war" between Remington and Browning?
Just FWIW, Browning was an independent inventor. Once he had an idea and a working model, he took it to whatever arms company would give him the deal he wanted, whether that was a flat purchase of the patent rights, a royalty arrangement, employment as a consultant, or some combination of those. Usually that involved the company lawyers writing the patent applications, and sometimes the company regretted that. Browning first offered the Auto 5 to Winchester, and their lawyers drew up and filed the patents for him. But he fell out with Winchester over royalty arrangements and took the gun to Remington. But Marcellus Hartley, head of Remington died while Browning was waiting to see him and Browning decided to go to Belgium and have them produce the gun.
Later, when Winchester wanted an autoloading shotgun, poor T.C. Johnson, Winchester's in-house designer, had to work around all those neat, tight patent specifications that Winchester's own attorneys had drawn up so carefully.
Last edited by James K; June 5, 2012 at 11:04 PM.