Lock in a Box
Inside an Anson & Deeley Boxlock Action
©SDH 2011

Ever since publication of the “Evolution of the Sidelock” in my book
Double Guns and Custom Gunsmithing, readers have been asking to see the insides of some boxlock guns. The most requested has been an Anson & Deeley boxlock. This was to be expected, as the A&D is without doubt the most frequently used boxlock design on the planet. Guns of this type have been manufactured in virtually every shop and factory producing British-style shotguns.

The A&D boxlock example shown is my M. Ogris, an Austrian-made 16-gauge that I’ve mentioned several times in the past. The photos were taken during a long-procrastinated strip cleaning, which required a total disassembly.

Some think the Westley Richards droplock is the highest evolution of the A&D design. The examples shown in the
Photo No. 4 are the droplocks from a .318-caliber double rifle from the collection of my friend Tim Crawford. These droplocks are virtually identical to those that would be found in a shotgun. The left lock, shown at the top, is cocked, while the right lock is shown in its fired position.
The Anson & Deeley boxlock action dates to a patent issued in 1875, when William Anson and John Deeley were in the employ of Westley Richards. Double-gun locks—either sidelocks or boxlocks—require a hammer, a sear, and a cocking lever powered by a mainspring and a sear spring. It is easier to show the parts of a sidelock, because the locks can be removed easily from the gun. In the photos on this page I’ve placed the parts on an outline of a boxlock action to illustrate their relationship inside the action.
Double shotguns evolved from muzzleloading guns with sidelocks—first flintlock and then percussion. They advanced into an era of external-hammer sidelock breechloading cartridge guns. The invention of a break-open shotgun action that housed all of the moving parts inside a compact frame was quite innovative. The invention required an internal cocking mechanism, as the hammers were no longer exposed for manual cocking. The original Anson & Deeley patent shows a drawing with internal cocking levers and, as if that might be too forward thinking, another illustration with a manual external cocking lever nestled in front of the trigger guard. Apparently, the internal mechanism worked well enough, as there are no known versions with the external cocker.

#1. Parts on drawing- copy
Photo No. 1: The firing mechanism of an Anson & Deeley-type boxlock action is composed of five moving parts. As shown in the fired position, they are: a) the hammer, or tumbler, in this example with integrated striker; b) the mainspring (uncompressed); c) the cocking lever; d) the sear spring; and e) the sear. Regardless of which company manufactures the action, when it is disassembled it will have these same five working parts, with minor variations.

#2. Parts, drawing, cocked - copy
Photo No. 2: The same parts in the cocked position, minus the mainspring.
A brief explanation of how the parts function: Opening the gun drops down the barrels, providing the power to rotate the cocking lever (c) and cock the hammer (a). The sear spring (d) pushes the front of the sear (e) into the full-cock notch on the hammer (a), holding it in the cocked position. The gun is fired by pulling the trigger, which lifts the sear tail, releasing the sear nose from the hammer notch. The hammer rotates forward under the mainspring tension to fire the gun.

#3. A&D fired copy-
Photo No. 3: The bottom of the action, with the inspection plate and trigger plates removed, shows the firing mechanism in the fired position with the cocking lever (c), hammer (a), sear (e) and sear spring (d).

#4. Westley Droplocks copy-
Photo No. 4: Invented some two decades after the A&D action, the Westley Richards droplock (patented in 1897 by John Deeley and L.B. Taylor while in the employ of Westley Richards) has the same parts as the boxlock but mounted on a lockplate (f) for easy removal from the gun. The right and left locks are shown as front and back with the hammer (a), mainspring (b), cocking lever (c), sear spring (d) and sear (e).

Droplocks are considered an improvement upon the basic A&D boxlock because the lock can be removed by turning over the gun and lifting out the bottom; it takes just a single finger. As stated in the patent, “the entire lock mechanism can be readily removed for cleaning or repair.” The bottom of the action has a hinged trapdoor with a spring-loaded button that is opened to access the locks. Be sure that the locks are cocked before removing or replacing them so that the tumblers are in the correct, rearward, position.
The Anson & Deeley action is the consummate boxlock action in terms of strength, simplicity, durability and manufacturing practicality. The actions are sometimes criticized for their boxy appearance, but some makers have managed to achieve elegance in that area. In fact, the A&D self-cocking boxlock has been so successful that it remains in production today—135 years after it was invented—by gunmakers around the world.