How to pick the right bullet for the right job for your AR-15
Knowing what ammunition to stuff in the magazine of an AR-15 depends on the task at hand. So often, we buy ammunition with the price exclusively in mind and give little consideration to the expectations placed on the bullet. If poking holes in paper is all that’s required, the cheapest ammunition available will certainly do. However, if pest control or home defense is the assignment, careful consideration of bullet weight and construction is a top priority.
Bullet weight matters because it effects the bullet’s velocity at the muzzle and the target. As a rule, heavier bullets will penetrate deeper and lighter bullets will open or expand faster (except in the case of full metal jacket projectiles) because lighter bullets are faster and heavier bullets have more inertia. Heavier bullets are harder to stop once they get going. Weight’s direct correlation with velocity is important because any projectile used for hunting or self-defense needs to hit with enough velocity to expand and give good terminal effects.
Lighter Bullets For Short Barrels
Short-barreled AR-15s (14.5 inches long and shorter) will usually be better served by bullets weighing 62 grains or less. The shorter the barrel, the slower the bullet fired from it because the hot burning gas that propels the bullet has less time and distance available to push. Lighter projectiles travel faster, so they can still expand as designed even when fired out of a slower, shorter barrel. 77-grain target bullets will work just fine from a shorter barrel, but there should be no expectation of bullet expansion or fragmentation except at very close distances (inside 100 yards – and even that is iffy).
Versatile Barrel Lengths
Barrels 16 inches and longer can shoot just about any bullet weight with satisfactory results. Heavier bullets benefit from the longer barrel and the time the gas has to push it on its way, so velocity increases with barrel length. If hunting with an AR-15 is a prime consideration, shoot with the longest barrel possible because the relatively small .223-caliber bullets need all the speed they can get to be effective. This holds true even with the heavier weight bullets and greater penetration that comes with them.
FMJs: Cost-Effective Range Ammo
There are some general rules about bullet construction that are invaluable when selecting which ammunition to buy. Full Metal Jacket (FMJ) projectiles are the cheapest to make and penetrate well, but yield minimal terminal effects and should never be used for hunting or self-defense. FMJ bullets are great for cheap blasting ammunition.
Polymer-tipped bullets usually have thin copper jackets and, thanks to the polymer tip, these bullets start to expand immediately on impact. These bullets are my top pick for self-defense and pest control. If I were using a 10- or 11-inch barreled AR-15 for self-defense, a 55- or 62-grain polymer tipped bullet would likely be my first choice. The light weight keeps the speed high even though it loses some velocity from the short barrel. The polymer tip means the bullet is almost guaranteed to expand or fragment inside the target. If my barrel stretched to 16 inches or longer, I’d use a 62- or 70-grain polymer-tipped bullet for the terminal effects on impact but leverage the heavier weight for better penetration.
Soft-point bullets also make a fine choice for hunting or self-defense. These bullets don’t expand as fast as their polymer-tipped cousins, but they do expand while offering better penetration from the slower expansion. One bullet that I always consider for self-defense or hunting is Speer’s Gold Dot. The Gold Dot bullet has an exposed lead nose with a copper jacket that is plated or bonded to the lead core. I like these bullets because if there’s ever a need to shoot through glass or sheetrock to hit the target, the Gold Dot will remain intact and not experience the lead core separating from copper jacket. Law Enforcement types call this an “intermediate barrier” scenario. Keeping the bullet in one piece is critical for it to perform well once it hits the target and the Gold Dot does this well.