Only after you have mastered your chosen rifle, and thoroughly ensured the reliability of your system, should you begin to worry about your defensive ammunition selection. Most of us would be better off practicing with what we have at hand than worrying about what ammunition to use. You should know you (the shooter), your rifle, your ammunition and what it can accomplish before considering yourself prepared for the defensive use of your rifle.
What makes a good defensive rifle load is the same performance characteristics we look for in any defensive ammunition. Those characteristics are: enough penetration to do significant damage, without too much penetration allowing the bullet to exit and go who knows where, and maximum expansion or fragmentation in order to cause the most damage. Some may want to choose, or already have on hand, a rifle chambered in a pistol caliber, commonly referred to as a carbine. A pistol caliber rifle will normally offer superior terminal ballistics, handling and ease of shot placement than the same caliber pistol due to the longer barrel, sight radius, and the fact that it has a buttstock. However, a carbine cannot match the performance of a true rifle caliber, even out of a short barreled rifle. A carbine might be considered for compatibility purposes if you have a pistol of the same caliber, or even the same magazine system. We must remember the important fact that a carbine is better than a pistol, the rifle you do not have, or harsh language, but should not be considered a substitute for a rifle.
While there are infinitely better choices than the .22 Long Rifle, the gun you have is a better defensive tool than the one you do not. If the .22 LR is all you posses to defend yourself, then reliability is an even greater concern than usual in your defense rifle. It is of the utmost importance to ensure your chosen load runs reliably in your rifle, as you do not have the margin of error that another, larger caliber would have. The second point to consider is the accuracy potential of your rifle, as the accuracy from rimfire rifles can vary greatly depending on the ammunition. There are hundreds of ammunition choices in .22 LR, and they vary little in terminal performance. The exceptions to this are the CCI Quick-Shock and the Aquila Super Colibri. These two loads and all exotic or “trick” ammo should be avoided due to inadequate penetration.
The AK-47 is the most prolific rifle in the world. Its predecessor, the SKS, is chambered in the same 7.62x39mm and has quickly become the choice for an inexpensive utilitarian rifle here in America, fighting to replace the wildly popular lever-action .30-30 Winchester Carbine. The military surplus imported ammo has long dried up, but the market has picked up where the surplus left-off, leaving us with plenty of inexpensive plinking ammo. Most of the inexpensive Russian JHP and JSP ammunition is substandard when asked to perform the role of defensive ammunition. The exception to the rule is ammo loaded using the 8M3 bullet, such as TulAmmo USA Hollow Point 124-grain (6-0315607), which offers acceptable ballistic terminal performance as a defensive cartridge. Winchester's excellent Super-X 123-grain soft point bullet (65102) load, BVAC 123 grain V-MAX (AMM-627) and Hornady’s 123 grain SST ammunition (0311377) are the other choice in this popular caliber to meet with our standards for a defensive load.
The .30-30 lever action has historically been one of the most popular rifles in North America. This cartridge offers similar terminal ballistics to expanding 7.62x39mm ammunition, and .30-30 Winchester generally outperforms the more modern .223 Remington. For inside-the-house defensive scenarios the Winchester Power-Shok 125-grain hollow point (65747) is the best choice, while for any outdoor use, a load with a heavier Jacketed Soft Point bullet like BVAC 170 Grain FSP (AMM-6690) is a much more flexible choice.
6.8mm Remington SPC
The 6.8mm Remington SPC (or 6.8x43mm) was developed with collaboration from individual members of US SOCOM, and is based on the .30 Remington cartridge which puts it between the 5.56x45mm NATO and the 7.62x39mm in bore diameter and velocity. It is readily adaptable to current 5.56/.223 firearm platforms, the cartridge overall length being comparable. Due to its rapid acceptance and popularity, there are already a bunch of great defensive loads for this relatively new cartridge. One of the best choices for a fighting carbine, and a fantastic general load, is the Hornady ammunition using the 110-grain OTM bullet (2-H8146). The Hornady 115-grain open tip match bullet used by Remington and SSA (2-SSA10072-SSA115OTM) dominated military terminal performance testing in 2002-2006 because, even at reduced impact velocities, it has excellent fragmentation and early yaw. Silver State’s load that utilizes the Sierra 110-grain Pro Hunter jacketed soft point bullet (2-SSA68PRO110) is a good general purpose bullet for defensive use and a great hunting load for medium size game. Bitterroot Valley also loads the Sierra Match King 115-grain (AMM-596), as does Remington (56318), this is another good choice for defensive use.
With the .223 Remington caliber, heavier bullet loadings are not necessarily better at closer, inside-the-home distances, unless that bullet is a fragmenting design. In this caliber, as in most, open tip match bullets (sometimes referred to as boat tail hollow points), jacketed hollow point and jacketed soft point designs can offer good terminal performance. If your rifle's barrel has a 1 in 7 twist rate, the Hornady 75-grain TAP (15463), Sierra 77-grain Match King boat tail hollow point in the Remington Premier (3-0311066), the Federal Gold Medal Match (6-0307937), and the Fiocchi Exacta Match (33154) are all good choices. If your rifle has a barrel with a twist rate of 1 in 9 inches that will not stabilize the heavy 70+ grain bullets, the 69-grain Sierra Match King bullet load by Remington (3-0309815), the Fiocchi (33135), and the 69 grain match boat tail hollow point load by Bitterroot Valley (AMM-271) are all good choices. Some other solid ammo choices for the ubiquitous 1/9 twist rifles are the 64 grain JSP from Bitteroot Valley (AMM-279), the Winchester Ranger 64 grain JSP (AMM-292), and the Federal Fusion 62 grain (59189). If you have the older 1 in 12 twist barrel, the best choices are the 55 grain bonded jacketed soft points or Federal's load with the Barnes 55 grain Triple-Shock X all copper bullets (3-0310494). These provide adequate penetration while using the lighter bullets.
With .308 Winchester, most heavy-bullet loads are ruled out due to over-penetration issues. After all, we do not want our bullets doing harm to anything or anyone beyond the target. The Hornady 155-grain TAP FPD (AMM-709) is probably the best choice in a defensive load in this caliber. Some other good loads for the .308 are the Winchester Vital-Shok utilizing the Nosler 150-grain ballistic tip bullet (67191), the Federal 150-grain Fusion (2-FEF308FS1), the Federal 165-grain Fusion JSP (3-0309399), the Winchester Supreme 168 grain Ballistic Silvertip (7-ASBST308A), Federal Vital-Shok with the 150 grain GameKing (6-0302466)and the Remington 165-grain AccuTip (56272).
For this ancient, proven, warhorse of a caliber, I recommend sticking with the same lighter bullets recommended for the .308 Winchester loadings. The Fiocchi Extrema (33226) with the 165-grain Sierra Game King, the Federal Vital-Shok with the 150 grain GameKing (6-0302464), the Winchester Supreme 168 grain Ballistic Silvertip (7-ASBST3006A), the 165-grain Federal Fusion (15752), 150-grain Fusion (15751), and the Federal Vital-Shock with the Nosler 150 grain ballistic tip bullet (67192) are recommended loads. If you are using your trusty M1, make sure you are shooting Garand-friendly ammunition, as most commercial loads are the incorrect pressure for your old rifle, and could damage it.