AR500 is the default answer for steel targets. AR550 costs a bit more and gets recommended in the same breath without anyone explaining the difference. The difference is hardness, and it only matters at one end of the spectrum — but at that end it matters a lot.
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What the numbers mean
AR stands for abrasion resistant, and the number is roughly the Brinell hardness. AR500 sits around 500 BHN, AR550 around 550.
Harder steel resists denting from fast impacts. That’s the entire practical difference. It isn’t about the plate breaking — it’s about whether the face stays flat.
Why a flat face is the whole point
A new plate is smooth, so bullets fragment and the splatter leaves predictably — down and out, away from you, assuming the plate is hung and angled correctly.
Once you start putting craters in it, that changes. A dimpled or pitted face turns into a set of little curved surfaces pointing in directions nobody planned, and fragments can come back at the shooter. A cratered plate isn’t just ugly, it’s the actual safety failure mode. It’s the reason hardness matters at all.
So the question isn’t “which lasts longer.” It’s which one stays safe under the ammo you’re actually shooting.
When AR500 is fine
Most of the time, honestly.
- Pistol, any reasonable distance
- Rimfire, all day, forever — .22 will basically never mark it
- Standard rifle rounds at sensible distance, where velocity has dropped off before impact
The usual guidance is to keep impact velocity under roughly 3,000 fps on 3/8″ AR500. Note impact, not muzzle — a round leaving at 3,200 fps has slowed considerably by 200 yards. Distance is doing a lot of the work.
For general range use with a mix of pistol and rifle, 3/8″ AR500 is the sensible default and what I’ve been shooting. The plate I ended up with is in this writeup — here’s the one I bought.
When AR550 earns the extra money
- Magnum rifle cartridges, or anything genuinely fast
- Close-range rifle — if you’re shooting rifle at 100 yards rather than 300, impact velocity is much higher and AR500 will start to mark
- High volume — a competition or class setting taking thousands of rounds, where you’d rather buy once
If you’re shooting pistol at 15 yards, AR550 is money spent for nothing. If you’re hammering a plate with a fast rifle round at 100 yards, it’s the right call.
Thickness matters as much as hardness
People fixate on 500 vs 550 and ignore this, which is backwards.
- 1/4″ — pistol and rimfire only. Rifle will deform or punch through it.
- 3/8″ — the standard for rifle. This is the one to buy if you’re buying one.
- 1/2″ — heavier, more forgiving, considerably more annoying to hang and carry.
3/8″ AR500 beats 1/4″ AR550 for rifle. If you’re choosing between spending on hardness or thickness, spend on thickness first.
Safety rules that apply to both
None of this is optional, and the harder plate doesn’t buy you out of any of it:
- Angle the plate downward. Hanging it flat sends splatter straight back along the firing line. A downward tilt sends it into the dirt. This is the single most important thing you’ll do with your target stand.
- Respect minimum distances. Follow what the manufacturer states for their plate — and if they don’t state any, that tells you something about the manufacturer.
- Eye protection, always. Fragments travel sideways further than people expect. Everyone at the line, not just the shooter.
- No steel core, no armor piercing, no green tip. Steel-cored projectiles will punch and crater any AR plate and create genuinely dangerous ricochet. This isn’t a durability question.
- Hang it so it can move. Chain or rubber straps let the plate swing and absorb energy. Bolting it rigidly to a frame transfers everything into the plate and the mounting holes, and holes are where plates fail.
- Retire cratered plates. Once the face is pitted, it’s done as a target. Run your hand over it — if you can feel craters, stop shooting it.
The short version
Buy 3/8″ AR500 unless you’re specifically shooting magnum rifle or close-range rifle at volume — then go AR550. Prioritize thickness over hardness, angle it downward, and retire it when the face pits.
And once you own steel, you’ll be hauling rifles to the range far more often, which is its own problem — I put off buying a proper rifle bag for way too long (the one I got).