Mortise lock vs cylindrical lock: how they differ and what has to match

This section and those after it, unless dated otherwise, were checked on 1 October 2026 against the sources listed on this page.

A mortise lock’s mechanism sits in a steel case set into a pocket cut in the door edge, and that case can throw a 1 in deadbolt as well as the latchbolt; a cylindrical lock is a chassis fitted through a hole bored across the door, with its latch in the edge. Each has its own standard: ANSI/BHMA A156.13 for mortise locks, A156.2 for bored locks.

Sargent makes both, so its two Grade 1 lines show the difference like for like, in Sargent’s own catalog figures:

Same job, different ANSI number

The two standards number lock functions separately. Sargent keeps its own function number across both lines, but the ANSI number changes with the standard: a storeroom lock is F07 in Sargent’s mortise catalog and F86 in its cylindrical one. Corbin Russwin’s ML2000 catalog uses the same mortise numbers: F01 passage, F04 entrance or office, F05 classroom, F07 storeroom, F22 privacy.

A shared function name does not mean the same behavior, so compare what each catalog says the levers and key do. Our lock function codes chart lists the cylindrical numbers; mortise cases are under Mortise lock cases by function.

BHMA’s public summaries of the two standards both state the Grade 1 durability test as 1,000,000 cycles with a 10 lb load and the lever torque limit as 28 in-lbf, but list fifteen security tests for A156.13 against seven for A156.2. A156.13 also has makers state an Operational Grade and a Security Grade separately, Grade 3 the minimum (its 2017 scope, as BHMA publishes it), which is why mortise catalogs quote two. Bored lock grades are explained in Grade 1 vs Grade 2 locks.

A mortise lock replacement fits without new cutting only when the case fits the pocket, the front fits its recess, and the lever, cylinder and thumbturn meet the holes already drilled through the door. Across the four commercial series below, the backset and front match; the spacing between lever and cylinder does not.

Read the lever-to-cylinder row first. On a door drilled for a Sargent or Accentra case, a Corbin Russwin or BEST case cannot meet both existing holes: one lands 1/4 in from the hole drilled for it, and the reverse holds too. The pocket is the smaller question. Sargent’s template 7057 cuts it 1-1/8 in wide and 4-9/16 in deep from the door edge, behind a recess 1-1/4 in wide for the front, and BEST states that the 45H case and faceplate fit the standard door preparation in ANSI A115.1. In the frame, Sargent, Accentra and BEST all set the strike’s centerline 3/8 in above the lock’s.

What else to read off the old lock and door:

• Knob or lever. Sargent’s 7800 (knob) and 8200 (lever) lockbodies can only be used with their own trim, so a knob-to-lever change on a Sargent door needs a new lockbody as well as the lever trim. BHMA’s summary of A156.13 says knob trim should be avoided on accessible routes.
• Rose or escutcheon. Accentra’s sectional trim bolts through holes in the case, while its escutcheon posts pass through the door above and below the case, 7-1/2 in apart on template 7088-1005, so changing trim style can mean new holes. See Lever trim, roses and escutcheons.
• The front. Sargent gives the outside front its own part number by function group (82-0080 for functions 12, 15 and 65, for example), and its lockbody-only order includes the front, strike and screw pack but no cylinder or trim. See Lock bodies and fronts.

Sargent, Corbin Russwin and Accentra each warn that any retrofit or field modification to a fire rated opening can affect its rating, and refer you to the code official; recutting a door for a different case is one. We supply listed hardware and confirm in writing the part number and options you have chosen. We are not code consultants; your Authority Having Jurisdiction (AHJ) makes the final call.

A mortise lock takes a threaded mortise cylinder whose length suits the door thickness and the trim, with the cam its function needs. Sargent’s standard is a #41 cylinder, 1-1/8 in long under the head, for single and double cylinder functions on a 1-3/4 in door; its Freewheeling trim takes a #46, 1-3/4 in long.

• Length. Sargent’s sizes run #41 1-1/8 in, #42 1-1/4 in, #43 1-3/8 in, #44 1-1/2 in and #46 1-3/4 in, up to #56 at 3 in, and its catalog pairs each size with a rosette or collar by trim and door thickness.
• Collars. Sargent requires a collar on functions with two cylinders and on cylinders longer than #41. Accentra sizes collars to the cylinder length, door thickness and trim, assumes a 1-3/4 in door when none is given, and needs the collar length specified when a cylinder is ordered on its own.
• Cam. Sargent fits one standard cam (13-0664) on every function except the 50 hotel function (-115 cam) and the inside cylinder of the 16 and 92 functions (-105 cam).
• Other makers’ cylinders. Corbin Russwin says the ML2000 accepts cylinders of most other manufacturers.
• Security grade. The cylinder can change it. Sargent states that LFIC and SFIC (interchangeable core) cylinders do not meet Security Grade 1 on the 8200, and BEST states that the 45H meets or exceeds Security Grade 2 with its 1CD core, and gives the 47H as Security Grade 1.

Cylinders on their own are listed under Mortise cylinders.