This proposed revision would align the Corps regulation with the regulations of the other Federal land management agencies by removing the need for an individual to obtain written permission before possessing a weapon on Corps projects,” the announcement explains.

Hunting and fishing during authorized seasons, in designated areas with proper licenses—and law enforcement—are the only exceptions under the current regulation. Comments will be accepted through June 12, 2020.
Reference: Army Corps of Engineers Considering Expanded Firearm Policy - American Rifleman