ANSI/BHMA A156.2 Bored and preassembled locks and latches
The knob and lever sets fitted through a cross bore. Grades 1, 2 and 3 by durability and strength.
What it actually decides
- Cycle life by grade. Allegion lists 1,000,000 / 400,000 / 200,000; other published tables give 800,000 for Grade 1 — cite the edition when quoting
- Impact resistance (hammer blows) by grade
- Backset 2-3/8 in or 2-3/4 in, cross bore 2-1/8 in
- Function designations (passage, privacy, entry, storeroom, classroom)
Applies to these lock types
Bored lever or knob set (ANSI/BHMA A156.2) · Single-cylinder deadbolt (ANSI/BHMA A156.36)
Why a retrofit designer cares
Because the bores are standardised, this is the family where a smart lockset can be specified without seeing the door.