Does that modification really help in any way?
The slide bevel was invented by 1950's NRA Match 1911 shooters.
These guys all reloaded, and just HATED the dents put in the case mouth of their brass.
In an attempt to prevent this, those who's guns did leave dents started putting a bevel on the 1911 ejection port, and Colt picked it up on their Gold Cup National Match.
After that, it just became another "gotta have" on a custom 1911, whether it did any good or not.
Today, we know that the "problem" can be cured by simply tuning the extractor and ejector.
In reality, the bevel has no real effect on on reliability, which most people who demand it think it does.
It was strictly so some guy in the 50's wouldn't have to straighten out his brass before running it through the sizing die.