I assure you that any quality .223 Ammunition from Hornady, Speer, Winchester, etc etc is going to do the job just fine. Same with 5.56. The .223 round has excellent ballistics against 2-legged targets, and has an excellent track record with law enforcement.
Now, I can't speak for the round in over-seas military usage. However, against unarmored opponents here at home, it's an excellent cartridge, and is more than capable of getting the job done. Not to mention there are tons of bullet types and weights to choose from for your desired application.
Comparing a trained sniper situation to a scared home owner is not realistic. Shot placement has a lot to do with a snipers killing efficiency with the .223. I am talking about stopping power. The .223 is one of the lowest rated rifle rounds for stopping power.
Here is a list Rifle Cartridge Killing Power
formula:
Energy at 100 yards (in foot pounds) x Sectional Density (taken from reloading manuals) x Bullet Frontal Area (in square inches) = Killing Power figure at 100 yards.
.223 WSSM(64 grain at 3600 fps) -
10.1
.243 Winchester(100 grain at 2960 fps) -
18.1
.243 WSSM(100 grain at 3100 fps) -
20.0
.25-06 Remington(120 grain at 2990 fps) -
26.5
6.5x55 SE(140 grain at 2700 fps) -
30.7
6.5mm Remington Magnum(120 grain at 3210 fps) -
30.2
.270 Winchester(130 grain at 3150 fps) -
35.0.270 Winchester(150 grain at 2850 fps) -
37.4
.270 WSM(140 grain at 3125 fps) -
40.1
7mm-08 Remington(140 grain at 2860 fps) -
33.6
.280 Remington(140 grain at 3000 fps) -
37.1
7mm Remington Magnum(150 grain at 3110 fps) -
44.8
.30 Carbine(110 grain at 1990 fps) -
7.4
.30-30 Winchester(150 grain at 2390 fps) -
22.8
.30-30 Winchester(170 grain at 2200 fps) -
25.4
.300 Savage(150 grain at 2630 fps) -
30.0
.308 Winchester(150 grain at 2820 fps) -
34.7
.308 Winchester(180 grain at 2620 fps) -
46.2
.30-06 Springfield(150 grain at 2920 fps) -
37.3
.30-06 Springfield(180 grain at 2700 fps) -
49.2
.300 WSM(180 grain at 2960 fps) -
59.5
.300 Winchester Magnum(180 grain at 2960 fps) -
59.5
.300 Weatherby Magnum(180 grain at 3240 fps) -
72.8
7.62x39 Soviet(123 grain at 2365 fps) -
15.7
.303 British(180 grain at 2460 fps) -
40.1
.32 Winchester Special(170 at 2250 fps) -
25.4
8x57 JS Mauser(195 grain at 2550 fps) -
52.0
325 WSM(200 grain at 2950 fps) -
75.6
.338x57 O'Connor(200 grain at 2400 fps) -
39.7
.338 Winchester Magnum(250 grain at 2650 fps) -
94.8
.357 Magnum (Rifle)(158 grain at 1830 fps) -
12.7
.35 Whelen(200 at 2675 fps) -
56.4
.350 Remington Magnum(200 grain at 2770 fps) -
60.9
.375 H&H Magnum(270 grain at 2690 fps) -
106.2
.416 Remington Magnum(400 grain at 2400 fps) -
188.4
.44 Remington Magnum (Rifle)(240 grain at 1760 fps) -
26.4
.444 Marlin(265 grain at 2325 fps) -
63.4
.45-70 Government(300 grain at 1810 fps) -
50.1.45-70 Government(405 grain at 1330 fps) -
55.0
.450 Marlin(350 grain at 2100 fps) -
88.9
.458 Winchester Magnum(500 grain at 2090 fps) -
217.3