Double Gun Bolting Systems
Rifle|November - December 2019
Spindles, Bites and Underlugs
Terry Wieland

The modern world of double rifles was shaped by three critical patents taken out in England in 1863, 1865 and 1875. Any high-quality double rifle you buy today, regardless of origin, will use at least one of these, probably two, and more than a few will use all three.

Not to stretch out the suspense, the first is the sliding bolt that locks into the barrel’s underlugs, patented by James Purdey (1862); the second is the top lever and spindle down through the frame to operate this sliding bolt, patented by William Middleditch Scott two years later; the third is the Anson & Deeley boxlock action developed at Westley Richards.

Obviously, a sidelock rifle will not use the third feature, but the first two are so ubiquitous on side-byside double guns and rifles of all descriptions, grades, makes and countries of origin that many shooters today don’t even believe they were ever new, revolutionary and subject to patent protection. “But that’s so obvious,” many riflemen will say. “Why would you do it any other way?”

Why, indeed? Well, like fire, the wheel and the whale-stay corset, truly brilliant ideas are characterized by the fact that to the generations that follow they look painfully obvious. What is not widely known is that, after Casimir Lefaucheux awakened English gunmakers to the possibilities of the break-action mechanism in 1851, it took more than a decade of intense activity to develop systems of bolting them closed that were workable and durable – never mind convenient and ergonomic – and another 15 years before the systems we now recognize as “obvious” came into general use.

The Lefaucheux hinges the barrels on a pin at the front of the action. They drop down to open the breech, and up to close it. Once closed, the barrels need to be locked in place using a method strong enough to withstand the stresses of firing, yet have a release mechanism that makes it easy to open, extract empty cases, reload and close. These stresses are essentially the same for both shotguns and rifles, although in the latter they are considerably greater.

In a double rifle, as the cartridge is fired the case presses to the rear against the standing breech while the bullet enters the rifling, striking it with tremendous force. This pushes the barrels forward but, since they are held in place by the hinge pin on the underside, the muzzles dip down and the barrels flex. In a side-by-side, each barrel sits to one side and they are fired separately, so there is lateral flexing as well. If you can imagine holding a writhing python with its many motions crammed into a few nanoseconds, you have an idea what this entails.

In the beginning, barrels had one underlug that mated with the hinge pin. This could be used as a locking lug as well, and with the low pressures of the early pinfires it worked well enough. Unfortunately, being situated several inches from the breech, it turned the barrels into levers, magnifying their downward movement on firing, tending to force the action open. This leverage was eliminated by adding a second lug closer to the standing breech, purely for locking purposes.

The second lug may have grown out of a design by Henry Jones, the Birmingham gunmaker who invented the Jones underlever, one of the best, and certainly the strongest, locking mechanisms of all time. This lever wrapped around the trigger guard and was swung out to the side to unlock the action. Internally, Jones lengthened the single lug, then milled a T-shaped slot into which the T projection of the lever locked. By giving the arms of the T a slant like a screw thread, the lever cammed the barrels down tightly as the lever swung closed.

Continue reading your story on the app

Continue reading your story in the magazine

MORE STORIES FROM RIFLEView All

MAUSER MODEL 1898

DOWN RANGE

4 mins read
Rifle
November - December 2021

THE HUNTER'S TRIGGER

LOCK, STOCK & BARREL

4 mins read
Rifle
November - December 2021

EOTECH VUDU 5-25X 50MM FFP

A RIFLEMAN’S OPTICS

6 mins read
Rifle
November - December 2021

WHY THE WINCHESTER PRE-'64 MODEL 70 STILL MATTERS

MOSTLY LONG GUNS

6 mins read
Rifle
November - December 2021

INDUSTRIAL REVOLUTION: THE SEQUEL

WALNUT HILL

6 mins read
Rifle
November - December 2021

H-S Precision PLR Rifle

Shooting the 6.5-284 Norma

8 mins read
Rifle
November - December 2021

AN INTERESTING OPEN SIGHT

LIGHT GUNSMITHING

5 mins read
Rifle
November - December 2021

6MM ARC

After using a 6.5 Grendel to cull a goodly number of Texas feral hogs, I’ve developed a great deal of respect for the cartridge. This has mostly involved nighttime forays shooting with thermal imaging optics. The 2.26-inch confines inherent to AR-15 magazines, and the Grendel’s limited case capacity, make 123- to 130-grain bullets the practical upper limit for such activities. These projectiles chug along at around 2,350/2,450 feet per second (fps), but deliver well out of proportion to its diminutive size.

9 mins read
Rifle
Fall 2021

.240 WEATHERBY MAGNUM

The .240 Weatherby Magnum gets little respect. Knowledgeable varmint hunters will spend a lot of dough to build up a custom 6mm-284 or one of the variations of the 6mm-06 wildcat rounds to get the ballistic features already available in a .240 Weatherby Magnum factory rifle: flat trajectory, good performance in wind and the ability to anchor larger game more reliably if called upon to do so.

7 mins read
Rifle
Fall 2021

6MM CREEDMOOR

The 6mm Creedmoor was designed for long-range target shooting with long and skinny, heavy-for-caliber bullets that slip through the air with the greatest of ease. Wind affects these bullets little; they just fly right through it, almost unaffected.

9 mins read
Rifle
Fall 2021
RELATED STORIES

Awl

“Awl” is from a series titled “Words I Did Not Understand.” Through memory—“the first screen of nostalgia”—and language, a writer pieces together her story of home.

10+ mins read
World Literature Today
Winter 2021

Caring for Your Loved Ones with COVID-19 at Home

Much has been reported about severe cases of COVID-19, but what about those who may be experiencing mild or lesser symptoms and are not in situations where they have to be hospitalized?

1 min read
The Best of Times
July 2020

AUTO ART

This year marks the 50th anniversary of my fascination with drag racing. During that time I have taught myself to draw, paint and make models of dragsters.

2 mins read
HOT CARS
Vol 4, Issue No.11, Spring 2020

The Postman's Hymn

Finish this shift, get to the next job, study for midterms, practice the sheet music for church, tuck Matt into bed….

3 mins read
Mysterious Ways
Apr/May 2020

AUTO ART

This year marks the 50th anniversary of my fascination with drag racing.

2 mins read
Model Car Builder
Vol 4, Issue No. 10, Spring 2020

Un Western moderno en Birmingham

‘Peaky Blinders’: venganza, redención y rock & roll

10+ mins read
Rolling Stone - México
Octubre 2019

FLYBE TO RESUME!

Airline back with new routes

1 min read
Daily Star
November 18, 2021

Opening up historic railway lines is our route to prosperity

‘By using existing lines, improved times will be delivered years earlier’

3 mins read
Daily Express
November 17, 2021

BEAUTIFUL SOUTH

There’s a wonderful sense of style and relaxed elegance in this hilltop home in Alabama – all courtesy of designer Sean Anderson

5 mins read
Homes & Gardens
December 2021

Nobel prize winner Malala marries in Birmingham

The activist and Nobel laureate Malala Yousafzai has announced she married yesterday in a small ceremony in Birmingham.

1 min read
The Guardian
November 10, 2021