Choosing rifle-rated body armour comes down to one practical question. What threats do you realistically need to stop, and how much weight and cost are you willing to carry to stop them? In the UK market the two ratings that cause the most confusion are NIJ III+ and NIJ IV. Both are hard armour plates built to defeat rifle rounds, but they sit at different points on the protection, weight, and price curve. This guide explains the difference in plain terms so you can match a plate to your actual use case.
A quick note on language. No plate is ever invincible. Armour is rated to stop specific projectiles at specific velocities under controlled test conditions. Outside those conditions, results vary. Throughout this guide, any protection level we mention reflects the manufacturer's stated rating and is not independently verified by R Supply Store.
Handgun versus rifle: where each rating sits
Before comparing III+ and IV it helps to see the full ladder. The older NIJ 0101.06 standard and the current NIJ 0101.07 standard both separate soft armour from hard armour.
- NIJ IIIA is soft armour. It is designed for handgun threats such as 9mm and .44 Magnum. It does not stop rifle rounds.
- NIJ III is hard armour rated for common rifle rounds such as 7.62x51mm NATO (M80 ball).
- NIJ III+ is not an official NIJ certification level. It is an industry term manufacturers use for plates that meet NIJ III and have also been tested against extra threats such as 5.56x45mm M193 at high velocity, which standard III testing does not cover.
- NIJ IV is the top hard armour level. It is rated to stop a single hit from .30 calibre armour piercing (M2 AP).
Under the newer NIJ 0101.07 standard, rifle protection is described using RF1, RF2 and RF3. In broad terms RF1 aligns with classic rifle threats, RF2 adds the 5.56 M193 and 7.62x39 mild steel core threats that "III+" was created to address, and RF3 covers the .30 calibre armour piercing threat that was previously called Level IV. As stock transitions, you will see both naming systems in the wild, so always read the threat list, not just the badge.
NIJ III+ in detail
A III+ plate is aimed at the buyer who wants broad protection against the rifle rounds most likely to be encountered, without the weight penalty of full armour piercing protection. Because "III+" is a manufacturer label rather than a certified tier, the exact threats covered vary between products. A good manufacturer will publish the specific rounds and velocities tested.
Typical III+ characteristics, manufacturer stated:
- Stops common lead core and mild steel core rifle rounds, often including 5.56 M193 and 7.62x39.
- Frequently lighter than a IV plate, especially in polyethylene or composite constructions.
- Generally a lower price point than IV.
- Will not reliably stop dedicated armour piercing rounds.
NIJ IV in detail
A NIJ IV plate is the highest commonly available hard armour rating. Its defining test is a single hit from .30 calibre M2 armour piercing. To defeat a hardened steel penetrator, IV plates usually use a ceramic strike face backed by composite. That construction tends to be heavier and more expensive, and ceramic plates can be more sensitive to drops and rough handling than some composite plates.
Typical IV characteristics, manufacturer stated:
- Rated to stop a single .30 calibre armour piercing hit.
- Usually heavier than an equivalent III+ plate.
- Higher price point.
- Many IV plates are rated for a single hit at that AP threat, so multi hit performance against AP can be limited.
III+ versus IV at a glance
- Threat focus. III+ targets the broad spread of common rifle rounds. IV adds dedicated armour piercing protection.
- Weight. III+ is usually lighter, which matters on long wears.
- Cost. III+ is generally cheaper. IV carries the ceramic and testing premium.
- Durability. Composite III+ plates can shrug off knocks that worry some ceramic IV plates.
- Best for. III+ suits most civilian, range, and general protective use. IV suits those with a specific, credible armour piercing threat.
Which one do you actually need?
For most UK buyers, the honest answer is that III or III+ covers the threats you are realistically planning for, at a weight you can wear for hours. Step up to IV only if armour piercing ammunition is a genuine part of your threat model, and you accept the extra weight, cost, and handling care that ceramic plates demand.
Whatever level you choose, the plate is only half the system. A plate has to sit in a carrier that fits, and many users pair hard plates with soft panels for added coverage. Browse our rifle rated hard armour for III, III+ and IV options, compare individual body armour panels and plates, and choose a host platform from our ballistic vests and carriers.
Fit, coverage and the rest of your kit
Sizing matters more than people expect. A plate that is too large restricts movement and may not seat correctly. The standard advice is to measure for the plate to protect your vital area from the suprasternal notch down, and to size the carrier to the plate. If head protection is part of your requirement, look at certified options separately, as helmet ratings follow their own threat scales.
Legal note for UK buyers
Owning body armour is legal in the UK and there is no general licence requirement for civilians. That said, you remain responsible for how you use and carry equipment. This guide is general information, not legal advice. Always confirm current rules for your situation before purchase.
Frequently asked questions
Is NIJ III+ an official certification?
No. III+ is a manufacturer term for a plate that meets NIJ III and has been tested against extra threats such as 5.56 M193. Always read the published threat list, because the exact rounds covered vary by product and are manufacturer stated, not independently verified.
Will a NIJ IV plate stop everything a III+ stops?
Generally a IV plate covers the standard rifle threats and adds .30 calibre armour piercing protection. However many IV plates are rated for a single AP hit, so multi hit performance against AP can be limited. Check the manufacturer's stated test results for the specific plate.
How do RF1, RF2 and RF3 relate to the old levels?
RF1, RF2 and RF3 are the rifle ratings in the newer NIJ 0101.07 standard. In broad terms RF1 aligns with classic Level III rifle threats, RF2 adds threats often associated with III+, and RF3 corresponds to the armour piercing protection previously called Level IV.
Do I need NIJ IV for civilian use?
For most civilian use in the UK, III or III+ covers the realistic threat set at a lighter weight and lower cost. IV makes sense only when dedicated armour piercing ammunition is a credible part of your threat model.