Understanding ASTM F3561

ASTM F3561 is a test method developed to evaluate the forced-entry resistance of fenestration systems after a simulated active-shooter attack.

The standard addresses a security problem that is different from conventional ballistic resistance alone.

In an active-shooter event, an attacker may use gunfire to damage or weaken a window, door, or other glazed opening and then attempt to physically breach that opening.

ASTM F3561 evaluates whether the system can continue functioning as a security barrier after ballistic weakening has occurred.

The fundamental question is:

After the fenestration system has been damaged by a defined ballistic attack, can it continue resisting forced entry?

This distinction is central to understanding the standard.

ASTM F3561 Is Not Simply a Ballistic Test

ASTM F3561 incorporates ballistic attack, but its primary purpose is not to establish a traditional bullet-resistant rating.

Instead, the ballistic portion of the test is used to weaken the security system before forced-entry evaluation.

The ASTM F3561 test methodology then subjects the weakened system to physical impacts.

This creates a two-stage security challenge:

Ballistic weakening
Forced-entry impact

A system must continue resisting passage after both forms of attack.

Engineering Principle

ASTM F3561 evaluates what happens after gunfire has already damaged the barrier. The objective is continued forced-entry resistance, not simply stopping the projectile.

Stage One — Ballistic Weakening

The first stage is intended to simulate the damage that gunfire can create during an active-shooter attack.

ASTM F3561 provides methods for weakening the test specimen using defined ballistic impacts.

In the test methodology represented in the standard and supporting test documentation, Method A uses 5.56 mm NATO, 55-grain, copper-jacketed lead-core ammunition with shot locations established by the standard.

This is an important point:

Penetration during the ballistic-weakening portion is not necessarily a failure of ASTM F3561.

The ballistic attack is being used to create damage that the system must subsequently resist during the forced-entry portion of the evaluation.

That is fundamentally different from UL 752, where preventing penetration is part of the ballistic performance objective.

Stage Two — Forced-Entry Impact

After ballistic weakening, the specimen is subjected to physical impacts using a standardized impact system.

The ASTM F3561 methodology uses a pendulum-type impactor with a weight of approximately 100 pounds.

The impact energy increases as the drop height increases.

The eight defined levels are:

Level 1 — 68 J / 50 ft-lbf at a 0.5 ft drop height
Level 2 — 136 J / 100 ft-lbf at a 1.0 ft drop height
Level 3 — 203 J / 150 ft-lbf at a 1.5 ft drop height
Level 4 — 271 J / 200 ft-lbf at a 2.0 ft drop height
Level 5 — 339 J / 250 ft-lbf at a 2.5 ft drop height
Level 6 — 407 J / 300 ft-lbf at a 3.0 ft drop height
Level 7 — 475 J / 350 ft-lbf at a 3.5 ft drop height
Level 8 — 542 J / 400 ft-lbf at a 4.0 ft drop height

Level 8 is the highest defined forced-entry resistance level in this eight-level system.

How the Forced-Entry Levels Progress

The levels represent increasing impact energy.

For window testing, the impact drop height begins at the lowest level and progresses to higher drop heights after two successful impacts at the same height.

This means the specimen is not simply struck once at the final desired energy.

It is progressively challenged at increasing impact levels.

A Level 8 result therefore represents successful resistance through the lower impact levels before reaching the highest defined impact energy.

Engineering Insight

The ASTM F3561 level represents the forced-entry impact energy resisted by a system after it has already been subjected to ballistic weakening.

What Constitutes Forced Entry?

The test is ultimately concerned with whether the attacker can create sufficient passage through the damaged security system.

This is important because the appearance of the glazing after testing can be dramatic.

Glass can crack extensively. Polymer layers can stretch or tear. Components may deform. Portions of the system may pull away from their original position.

Visible damage alone does not necessarily mean the barrier has failed.

The relevant question is whether the defined test shape can pass through the opening created by the attack.

Breakage and breach are not the same thing.

ASTM F3561 Evaluates Fenestration Systems

One of the most important aspects of ASTM F3561 is that the standard is written around fenestration systems, not simply pieces of glass.

Systems submitted for testing are intended to be representative of production systems and include the required anchoring and operating components.

Depending on the assembly, performance can involve:

Glazing
Frames
Glazing retention
Anchors
Fasteners
Door panels
Locks
Latches
Hardware
Mullions
Connections between components

This matters because an attacker does not necessarily attack only the center of the glass.

The security of the complete opening depends on the interaction of all of these components.

Different Systems Require Different Attack Locations

ASTM F3561 recognizes that different fenestration systems have different potential vulnerabilities.

For example, the standard contains different attack procedures for doors, windows, and panels.

Window testing includes forced-entry impacts applied to the glazing.

Panel testing can include impacts at the center, corner, and frame-pocket areas.

Door testing can include glazing attacks as well as attacks involving the lock or latch area.

This system-level approach is important because the strongest glazing material cannot compensate for a weak frame, lock, attachment, or retention condition.

Glazing Testing and Complete-System Testing Are Not Interchangeable

This distinction deserves particular attention when reviewing test reports.

A glazing material may be evaluated independently to understand its performance, but that result should not automatically be applied to every door or window system using that glazing.

For specifiers and designers, the key question should be:

What exactly was tested?

Was it:

The glazing material?
A complete window?
A door?
A panel system?
The glazing and frame together?
The lock and hardware?
The complete installed assembly?

The answer can materially affect how the test result should be interpreted.

ASTM F3561 and UL 752 Answer Different Questions

ASTM F3561 should not be confused with UL 752.

UL 752 asks:

Can the product resist a defined ballistic threat according to the applicable ballistic requirements?

ASTM F3561 asks:

After a defined ballistic attack has weakened the system, can the system continue resisting forced entry?

A system can therefore perform very differently under the two standards.

A product does not need to be a traditional UL-listed bullet-resistant glazing product simply because it is being evaluated under ASTM F3561.

The ballistic portion of ASTM F3561 serves a different purpose: creating standardized damage before the forced-entry attack.

ASTM F3561 and ASTM F1233 Also Answer Different Questions

ASTM F1233 and ASTM F3561 both address forced-entry resistance, but their methodologies are substantially different.

ASTM F1233 uses progressive attacks involving various tools and attack methods to evaluate cumulative resistance to physical breach.

ASTM F3561 begins with a simulated active-shooter ballistic attack and then evaluates the weakened system using standardized forced-entry impacts at increasing energy levels.

ASTM F1233 therefore provides information about resistance to prolonged physical attack.

ASTM F3561 provides information about the ability of a fenestration system to continue delaying entry after ballistic damage.

Neither test should automatically be treated as a substitute for the other.

Why Testing to Both Standards Can Be Valuable

For some security applications, understanding performance under both ASTM F1233 and ASTM F3561 can provide a more complete picture of forced-entry resistance.

ASTM F3561 addresses the specific sequence of ballistic weakening followed by impact attack.

ASTM F1233 subjects the security barrier to a broader range of progressive physical attack methods.

A system that performs well under both methodologies has therefore demonstrated resistance under two different attack scenarios.

This does not make the standards equivalent.

It means they provide complementary information about the performance of the security system.

What Level 8 Means

Level 8 represents the highest forced-entry impact level defined in the eight-level ASTM F3561 system.

At Level 8, the impactor is released from a height of 4 feet, producing approximately 542 joules or 400 ft-lbf of potential energy.

But the number should not be considered in isolation.

A Level 8 system has first been subjected to the ballistic-weakening procedure and then must continue resisting the prescribed forced-entry impacts through the increasing energy levels.

The significance of Level 8 is therefore not simply that a 100-pound impactor was released from four feet.

It represents the system’s ability to maintain the required barrier performance after ballistic damage and through the progressive forced-entry impact sequence.

ASTM F3561 Does Not Mean a System Is “Active-Shooter Proof”

No security glazing system should be described as universally “active-shooter proof.”

ASTM F3561 establishes a repeatable test methodology representing a defined attack scenario.

Real-world attacks can differ in:

Firearms
Ammunition
Number of shots
Shot locations
Number of attackers
Physical attack methods
Attack duration
Building configuration
Installation
Door and hardware conditions
Surrounding construction

Testing therefore provides a standardized basis for evaluating and comparing security systems.

It does not guarantee the outcome of every possible real-world event.

Active-Shooter Glazing Is About Creating Time

The purpose of ASTM F3561-resistant glazing is not to make a building impossible to enter.

The purpose is to help maintain the security barrier after ballistic damage and delay physical entry.

Additional time can allow:

Occupants to move away from the threat
Classrooms or interior areas to be secured
Emergency procedures to be initiated
Communications to occur
Law enforcement or security personnel to respond

Active-shooter resistant glazing should therefore be considered part of a broader layered security strategy rather than as a standalone security solution.

Why Test Reports Matter

A statement that a product is “ASTM F3561 tested” does not provide enough information by itself.

Useful test documentation can identify:

Standard and edition
Test method
Specimen configuration
Whether glazing or a complete fenestration system was tested
Ballistic weakening method
Ammunition
Shot pattern
Forced-entry impact level
Impact locations
Number of impacts
Passage criteria
Laboratory
Test date
Reported result

The rating level and scope of the tested assembly are particularly important.

A glazing-only result should not automatically be represented as performance of a complete door or window system.

Key Takeaways

ASTM F3561 evaluates forced-entry resistance after simulated active-shooter ballistic damage.
The test combines ballistic weakening followed by forced-entry impact testing.
The ballistic portion of the test is intended to weaken the system; ASTM F3561 is not simply a traditional ballistic-resistance test.
Penetration during the ballistic-weakening stage is not necessarily a failure of the ASTM F3561 methodology.
Forced-entry resistance is evaluated at progressively increasing impact-energy levels.
The eight-level system ranges from Level 1 at 50 ft-lbf to Level 8 at 400 ft-lbf.
Level 8 is the highest defined forced-entry impact level in that system.
Visible damage does not necessarily mean the security barrier has failed.
ASTM F3561 is fundamentally concerned with fenestration-system performance, including glazing, framing, retention, hardware, locks, and anchorage.
Glazing-only testing should not automatically be applied to every door or window system using that glazing.
ASTM F3561, ASTM F1233, and UL 752 address different security questions and should not be treated as interchangeable standards.
Testing to both ASTM F3561 and ASTM F1233 can provide complementary information about forced-entry performance.
The practical security objective is delay—maintaining the barrier long enough to create additional response time.

Continue Learning

PA-EF-006 — Active-Shooter Glazing Explained

Understand how security glazing fits into a broader strategy for delaying active-shooter entry.

PA-EF-002 — What Is Forced-Entry Resistant Glass?

Learn the fundamental engineering principles behind glazing designed to remain a barrier after damage.

PA-EF-005 — Bullet-Resistant vs. Forced-Entry Resistant Glazing

Understand why ballistic resistance and forced-entry resistance address different security objectives.

PA-TS-002 — Understanding ASTM F1233

Explore progressive physical-attack testing and cumulative forced-entry resistance.

PA-TS-001 — Understanding UL 752

Learn how ballistic resistance is evaluated against defined projectile threats.

PA-PT-006 — Forced-Entry Resistant Laminates

Explore the laminate materials and construction approaches used to provide resistance to sustained physical attack.

PA-TS-003 Understanding ASTM F3561