As already said, it's just a vent (flash hole) punch burr. Bigger than usual, but basically just a little bit of extra brass in the case. Not likely enough to matter. I wouldn't even bother deburring it unless you are just curious to see if you can detect a performance difference. I like playing with that kind of thing, but I wouldn't expect an issue in this case. The powder space under the bullet in a .45 Auto is so small and the distance from the vent to the bullet base is so small the primer will pressurize and ignite the powder just fine as it is, same as it did for the original factory load that it came with.
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