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While the cement abutment and steel utility pole are not the ideal cover, they are likely to stop pistol bullets and buckshot. Poking the muzzle past cover reduces concealment but cuts down on the muzzle blast reflection. Poor visibility to the left requires an overwatch to prevent flanking by rioters.
An SBR with 8.1″ barrel and a sound suppressor cuts down the velocity to about 2400fps (with 55gr ammunition), below fragmentation range for military ball. Solution: load up expanding hunting bullets, like Barnes TSX. With the 1x prismatic scope shown and even more so with red dots, sighting is faster than with iron sights. The entire gun fits into fairly small bags, especially with a 20rd magazine inserted.
Again, the dumpster only protects against buckshot and pistol bullets. Stopping rifle fire requires a bit of luck with the angles. On the plus side, it offers a convenient steady firing position high enough above ground to see a ways out. Pulling back about six inches would better safeguard the forward hand from ricochets.
Again, poor visibility to the left and lack of protection from the right pretty much requires an overwatch. A small team can succeed where several unconnected individuals would likely fail.