Whether body armor can stop armor-piercing rounds matters most to the people who wear it at work: law enforcement officers, and the agencies and buyers who equip them. The honest answer depends on which round, and on what the armor was tested against.
Not all body armor is rated for the same threats. A rating names a standard, a level and the rounds behind that level, and that is where the answer to this question lives.
Understanding body armor basics
NIJ describes soft body armor as working by catching the bullet in a web of very strong fibers that absorb and disperse its energy. Soft armor is made from fiber families such as aramids, sold under trademarks such as Kevlar and Twaron, and ultra-high-molecular-weight polyethylene (UHMWPE). Hard armor adds a rigid plate, made of ceramic, steel or polyethylene, alone or in combination.
The protection a model offers is what it was tested against, under a named standard. The material alone does not tell you that.
NIJ has published its own count of what armor has done in the field: in October 2006, it wrote that the body armor its standards and testing cover had been in use for 30 years and had saved at least 3,000 officers' lives. For the longer story, see the history of bulletproof vests.
Side note: body armor also includes helmets and shields, which are tested under their own standards, not the body armor standard. For carriers, see exploring different types of plate carriers.
What are armor-piercing rounds
There are two meanings, and they are worth keeping apart.
- In NIJ testing, the armor-piercing round is a specific rifle round: the .30 caliber M2 AP, a U.S. military round. It is the test round for Level IV under NIJ Standard 0101.06 and for RF3 under NIJ Standard 0123.00, which sets the levels for 0101.07.
- In U.S. federal law, "armor piercing ammunition" is defined for handguns by what the projectile or its core is made of, such as tungsten alloys, steel, iron, brass, bronze, beryllium copper or depleted uranium, or by a heavy full jacket (18 U.S.C. § 921(a)(17)). Federal law restricts the manufacture and import of ammunition that meets that definition, with exceptions (18 U.S.C. § 922(a)(7)). This is orientation, not legal advice.
The NIJ test round and the legal definition are not the same thing: one is a rifle round named in a standard, the other a definition aimed at handgun ammunition.
How armor stops a round
NIJ describes the fibers in soft armor as absorbing and dispersing the bullet's energy, with each layer absorbing more, while the bullet deforms. A ceramic rifle plate puts a very hard strike face in front of a fiber backing: the ceramic breaks up and blunts the round as it shatters, and the backing catches the fragments.
For more on what plates are made of, see materials used in armor plates.
Combinations of materials (a hard strike face over a fiber backing, or a plate worn with soft armor) are common in hard armor. Whatever the construction, the NIJ test is run on the whole plate, by model.
Different levels of body armor
Levels are defined by standards. Under NIJ, there are two sets in use. NIJ 0123.00 maps some old levels to new ones (RF1 replaces Level III; RF3 replaces Level IV), but a model's listing does not carry over: a model is listed under 0101.07 only once it has been tested to it.
| NIJ 0101.06 | Test rounds (0101.06) | NIJ 0123.00 (for 0101.07) | Test rounds (0123.00) |
|---|---|---|---|
| IIA, II, IIIA | handgun rounds | HG1, HG2 | 9mm Luger and .357 Magnum (HG1); 9mm Luger and .44 Magnum (HG2) |
| III | 7.62 M80, 147 gr, at 2,780 ft/s | RF1 | 7.62 M80, 7.62x39 MSC and 5.56 M193 |
| (none) | RF2 | the RF1 rounds plus 5.56 M855 | |
| IV | .30 M2 AP, 166 gr, at 2,880 ft/s | RF3 | .30-06 M2 AP, 165.7 gr, at 2,880 ft/s |
0101.07 retired Level IIA. 0101.06 is not expired: NIJ stopped accepting new 0101.06 models for testing on 5 January 2024, and anticipates maintaining the 0101.06 list through at least the end of calendar year 2029.
So the NIJ levels tested against an armor-piercing round are Level IV (0101.06) and RF3 (0101.07). What that test shows is that the model met the standard against that one round, at that velocity, with the number and placement of shots the standard sets. It says nothing about other armor-piercing rounds, which no NIJ level tests. "Level III+" is an industry term, not an NIJ level: no standard defines the plus, so read the specification and test report behind it. For more, see what can Level IV body armor stop.
Tests and their results
A ballistic test is controlled: named rounds, a set velocity, set shot placement, and a clay backing that records how far the armor was pushed in. Under NIJ 0101.06, the number of shots on each Type IV panel depends on how many impacts the manufacturer says the model withstands: a model rated for a single impact is tested on more panels.
A test is a test of that model, against those rounds, under those conditions. It does not cover every angle, distance or round a wearer could meet, and it does not cover a different model.
For a model on the NIJ Compliant Products List (CPL), the listing records its standard, level and status. For anything else, including armor tested to another standard, the evidence is the test report from the laboratory that tested it: the round, velocity, number of shots and result.
Factors influencing effectiveness
A level belongs to the model as tested. Outside the test, the armor's condition, coverage and fit all bear on how it is worn and what it covers.
CJTTEC, which administers the Compliance Testing Program for NIJ, advises inspecting armor, storing it as the maker instructs, avoiding extreme heat such as a vehicle trunk, and replacing a vest struck by a bullet immediately. It also warns that a plate's good appearance does not mean good performance. For more, see does temperature affect body armor performance.
Coverage and fit matter too: armor only covers what it covers. For guidance, see the right way to fit body armor.
Innovations in body armor technology
New materials keep arriving. In its 2011 report for the Army, the National Research Council counts ceramics among the materials that have reduced the weight of armor for personnel.
We found no NIJ or CJTTEC source that ranks materials, composites or newer technologies against armor-piercing rounds (checked 1 October 2026). A new material changes what a model is made of, not what it was tested against: the listing or the test report still answers that.
Practical considerations for use
Our advice: start from the threat you assess for the role, then find armor tested against those rounds, under a standard your agency, policy or funder accepts. Where a buyer or funder requires an NIJ listing (the federal Bulletproof Vest Partnership does), check the exact model on the CPL and note the date you read it. Where it does not, ask for the standard, the level and the test report.
Weight and comfort matter because armor that is not worn protects no one. Weigh them against the threat, not against a label.
Follow CJTTEC's care guidance and the maker's instructions for inspection, cleaning and storage.
Conclusion
Body armor can be tested against an armor-piercing round. Under NIJ, that round is the .30 caliber M2 AP, and the levels tested against it are Level IV (0101.06) and RF3 (0101.07). A listing or test report at one of those levels tells you how the model did against that round, in that test.
Read the round, the standard and the shot count before the label. ArmorList's product records show the standards a model is recorded as tested to and, for NIJ, its CPL status with the date the list was read.
Sources
- NIJ, Ballistic Resistance of Body Armor, NIJ Standard-0101.06 (read 2026-09-29)
- NIJ, Ballistic Resistance of Body Armor, NIJ Standard-0101.06 (PDF) (read 2026-10-01)
- NIJ, Specification for NIJ Ballistic Protection Levels and Associated Test Threats, NIJ Standard 0123.00 (read 2026-09-29)
- NIJ, NIJ Standard 0123.00 (PDF) (read 2026-09-29)
- NIJ, NIJ Standard 0123.00, Addendum 2 (read 2026-09-29)
- NIJ, Ballistic Resistance of Body Armor, NIJ Standard 0101.07 (read 2026-09-29)
- NIJ, Compliant Products List: Ballistic Resistant Body Armor (read 2026-09-29)
- NIJ, 30 Years, 3,000 Saves (October 2006, NCJ 217202) (read 2026-09-30)
- NIJ, Selection and Application Guide to Personal Body Armor, NIJ Guide 100-01 (PDF) (read 2026-09-30)
- NIST, Personal Armour Systems Symposium 2018 proceedings (read 2026-09-25)
- National Research Council, Opportunities in Protection Materials Science and Technology for Future Army Applications (2011) (read 2026-09-30)
- CJTTEC, Body Armor Care and Replacement (read 2026-09-30)
- CJTTEC, NIJ Standard 0101.07 Information (read 2026-09-29)
- 18 U.S.C. § 921(a)(17), definition of armor piercing ammunition (read 2026-10-01)
- 18 U.S.C. § 922(a)(7), manufacture and import of armor piercing ammunition (read 2026-10-01)
- BJA, BVP Frequently Asked Questions (PDF, updated September 2025) (read 2026-09-29)