The M4, with a scope, will effectively reach man torsos a lot further than it makes any sense to shoot at them, civilian-shtf. I'll take a shorter barrel with sound suppressor, over just a longer barrel (noisy) any day! Being heard to a maximum of half a mile (more likely 1/4 mile) rather than 1.5 miles, can make a big difference in your longevity, if hostiles are about Troops miss with thosuands of rds for every hit that they get with the rifle, and a big reason for that is flinching from noise/flash at night. Also, the noise and flash locate you for the enemy, making your firing hasty/error-prone. A good suppressor changes things dramatically.
Use 60 gr Aquila subsonic .22 ammo in the Ciener .22lr unit in the 223, and you can brain men,deer, or cattle to 50m, and be a lethal threat to 100m+. When you know to hold shut the bolt with your non firing thumb, the .22 thru the 223 suppressor, sounds like a BB gun. The bullet's hitting the target makes a lot more noise than is present at the muzzle! You can hear the 'thwock" when you hit a rabbit, for instance.
When you know enough to have luminous sights, and avoid being out in daylight, the suppressed .22 takes on an entirely new aspect. When you can't tell where you're taking fire from, you also can't tell which side of the tree constitutes cover! That means more shots at still stationary targets once the firing starts, which means more hits. Let the "hittees" howl and scream for a few minutes, until their buddies shoot them and take their stuff.
