That part of the barrel acts as receiver (A) with vertical breech (B) [plug] are heat treated, case hardened steel.  The Ferguson breech is different from any other. Loading though the breech's 7/8-inch vertical opening (C), the sphere rolls forward until stopped by a lip, or venturi shoulder radius, or taper, or by its engaging the barrel's rifling. Projectiles seal the barrel from windage - that is, from propulsion gases blowing ahead of the ball on its way out of the muzzle - an unfortunate but normal occurrence when loading from the muzzle. The vertical breech does not - repeat, does not - serve the same purpose as does a cartridge rifle's breech bolt. There is no stress or pressure from ignition [that threatens] to blow the breech bolt from the mechanism. There is no brass gasket that must be precisely supported. The breech must deal with imperfect gas seals at its top and bottom. Long term, this is a wear resistance problem, not a strength problem. (Taken from Ferguson's book circa 1888.)[1]

 

Enigma explained? [2]
Before the American Revolution ended in 1783, the progress of Britain's war effort, including what led to King's Mountain, raised questions, some of them by General Washington. The common denominator among them was: General Sir William Howe and his political associates.

As early as 1781, a prominent Englishman, Joseph Galloway, accused Howe of "losing the war on purpose." He charged that Howe, a member of Britain's Whig Party, had been an American sympathizer for years. When Howe had stood for Parliament in Nottingham in 1775, he said he would never fight against the Americans. But when the King ordered him to Boston, Howe could not refuse.

For years Americans had wondered why every time Howe had the Continental army nearly beaten, he refused victory. Squandered opportunities included: Long Island, where he had to issue repeatedly his order to halt his troops, preventing them from storming Brooklyn Heights; White Plains; Chatterton's Hill; Brandywine, where he could have followed up and destroyed Washington's army; and Valley Forge, when the Americans were sick, nearly helpless, and low on rations and ammunition. After Long Island, American General Israel Putnam said, "General Howe is either our friend or no general."

By Howe's own admission, he may have had political reasons for ordering Ferguson's breech-loading rifles into storage after their excellent performance at Brandywine. Political reasons caused him and other like-minded people to make sure that only 200 or so Ferguson rifles were produced. And political reasons caused him to ensure that his successor, General Sir Henry Clinton, would be reluctant to release more than 40 rifles from storage in a New York cellar.

Types of Fergusons

1776 Pattern – This was Patrick Ferguson’s original weapon.  The Fergusons brought to Chile by Ceurôtte were of this type.

1821 Pattern – This is Don Carlos’ first copy of the 1776 pattern.  Except for the armoury stamp, it is the same as the 1776 pattern.

1823 Pattern – This is Don Carlos first innovation.  The 1776 and 1821 patterns used a very fine and very intricate double thread in the plug.  The fine thread was easily clogged with powder residue and caused the plug to stick after 20 to a hundred uses.  Don Carlos’ design was for a coarser thread that was less susceptible to powder residue, but also required more than one turn to open the breech.  This decreased speed and efficiency and improved durability.  The decreased speed in loading was still an improvement over the muzzle-loaders of the day.

1851 Pattern – This was used by the United Republics’ forces in the Crimea.  The 1823 Pattern was fitted with a percussion hammer in the early 1840’s.  The 1851 pattern was the first design made with a percussion cap rather than fitted with one.