Precision FB277 Fire Bolt Assembly

The Precision FB277 is the fire bolt assembly used in Precision Hardware (PHI) fire-rated exit devices across the 2000 series vertical rod product family. If you've been searching "fb277" and need to confirm this is the right part, or you've been looking for a "fire bolt" or "fire bolt assembly" for a PHI Apex device - this is it. Precision Hardware is now part of the dormakaba/BEST Access Systems group, so you may see this part referenced under Precision, PHI, or BEST depending on where the specification was written.

What a Fire Bolt Assembly Does

The fire bolt assembly is the component that gives a vertical rod exit device its fire-rated classification. On a standard panic exit device, the door closes against its latchbolt and the top rod engages the top strike. That's enough for code-compliant egress but not enough for a fire door.

Fire-rated vertical rod exit devices need to positively latch the top of the door to the frame when the door closes - not just touch it, but latch it with enough force to resist the positive pressure that builds on the fire side of a door during an active fire event. The FB277 fire bolt assembly provides that top-latch mechanism. When the door swings closed, the fire bolt automatically engages the top strike and creates a mechanically secured seal point at the top of the door. This is what allows the Precision 2200 series and related fire-rated devices to carry UL10C (positive pressure fire test) listing and meet NFPA 80 fire door assembly requirements.

On non-fire-rated Precision 2000 devices, the FB277 is not included. The device label tells you which version you have: a label reading R7639 means you have a fire-rated device that should have the FB277 installed. A label reading 335L means it's non-fire-rated and the fire bolt assembly doesn't apply.

When You're Ordering This as a Replacement Part

The FB277 ships standard with new fire-rated Precision 2000 series devices at the factory. If you're ordering it separately, you're likely replacing a damaged, missing, or worn fire bolt assembly on an existing installation, or you're adding fire-rated capability to an existing device as part of a code upgrade.

Before ordering a replacement, confirm the existing device carries the fire rating label (R7639). If the device was originally non-fire-rated, adding an FB277 by itself won't bring it into compliance - the device body itself needs to be the fire-rated version. This is a common mistake when facility managers are trying to bring older panic hardware up to current fire inspection standards.

Compatible Precision Device Series

The FB277 fire bolt assembly is used across multiple Precision Hardware exit device families:

Precision 2000/2200 Series - Apex touchbar surface vertical rod exit devices, all fire-rated configurations

FL2200 Series - Flat bar fire-rated surface vertical rod devices

Precision 2600/2700 Series - Fire-rated concealed vertical rod exit devices

Precision 100/200/300 Series - Earlier PHI fire-rated devices (confirm compatibility with your specific model)

All of these platforms use the FB277 as the standard fire bolt assembly across fire-rated configurations.

Specifications

Model: Precision FB277

Also Referenced As: PHI FB277, BEST FB277

Type: Fire bolt assembly (exit device component/replacement part)

Function: Positive-pressure top latching for fire-rated vertical rod exit devices

Fire Rating: Required component for UL10C and NFPA 80 compliant fire door assemblies

Compatible Devices: Precision 2000/2200/FL2200, 2600, 2700 Series fire-rated exit devices

Manufacturer: Precision Hardware Inc. (PHI), dormakaba/BEST Access Systems

Origin: Made in USA

American Locksets has stocked Precision Hardware and PHI exit device parts since 2001.