Trial and Error: Experiments with 6-pdrs

Yesterday I left off discussing correspondence between the Ordnance Board and the Secretary of War Joel Roberts Poinsett in 1840.  In his letter of March 5, 1840, Poinsett instructed the Army officers to drop their desired compatibility with older guns, with regard to carriages.  This released designers from length and weight restrictions, leading to a sturdy and successful field piece – the Model 1841.

As the Ordnance Board considered the redesign, the officers weighed technical data gained from nearly a decade of tests and observations.  The chart below, complied from Field Artillery Weapons of the Civil War and The Big Guns (see sources below), summarizes the deliver of experimental 6-pdr guns in the 1830s and 1840s.  (Some of which are outside the scope of this post, but we may revisit them later).

Starting with the top four lines, I briefly mentioned the iron Columbia guns cast in 1833, the bronze West Point guns of 1832, and the West Point iron guns of 1835 in a previous post on the “iron age” guns.  These served to define the exterior form and to some degree the idea weight of the guns.

Recall that concurrent to the bronze Model 1835, Alger delivered a batch of “malleable iron” guns for tests, which are shown in the table as “Pattern of 1836.”   West Point also provided a single gun of similar construction that year.  “Malleable iron” in this sense likely referred to several different varieties of the metal achieved using different annealing processes (in short, involving the removal of carbon from the iron mix).  The Ordnance Manual of 1850 defines several varieties of iron – some if not all of which were tested during this period – “gray,” “white,” and “mottled.”  Not mentioned by name in the 1850 manual, but considered the common American variety at the time was “black.”  This differed from “white,” which was the common European variety, in the atmosphere used to remove the carbon.   (I could go into that more, but, alas I did NOT stay at a Holiday Inn Express last night.  Feel free to read more in the Foundryman’s Handbook.)

It is possible the pattern 1836 and later pattern 1838 experimental guns were each cast to order with different varieties of iron.  The weights indicate similar dimensions, if not forms, to the contemporary bronze weapons.   But few of these cannons survived the tests and later scrap drives.  Thankfully, the ordnance officers did record the results of the destructive tests.   My friend John Morris recently posted some drawings  he found in the National Archives to the Company of Military Historians Forum (again a shameless plug for that fine organization) showing the results of tests conducted in 1839.  All told fourteen drawings, of which six depict burst or failed 6-pdrs. In the order presentation on John’s Photobucket slideshow (password is “attack”), here are the particulars:

  • First slide – a bronze 6-pdr weighing 684 pounds, which may be a Model 1838 tested to dramatic failure.
  • Second Slide – two iron 6-pdrs and an iron 12-pdr howitzer.  Alger 6-pdr registry number 3 weighing 698 pounds and a “Parrott” (West Point?) 6-pdr registry number 9 weighing 675 pounds.  All showing failure cracks.  These match to the experimental Pattern of 1838 in the chart above.
  • Slide eight – Alger 6-pdr cast iron (annealed), registry number 7, weighing 692 pounds.  Burst, rather dramatically, after 94 fires.  Again weights matching the Pattern of 1838.
  • Slide nine – Alger 6-pdr cast iron (annealed), registry number 5, weighing 697 pounds.  This Pattern 1838 surviving up to 260 fires.
  • Slide ten – Parrott (West Point) 6-pdr iron, number 8, weighing 684 pounds which burst only after extreme testing.
  • Slide eleven – Alger 6-pdr, registry number 6, weighing 706 pounds which also survived until extreme testing.

The drawings account for six of the twenty-six iron guns tested 1837-39 (plus one of the bronze guns), and provide a rather graphic depiction of what “gun failure” means.  Note also the last drawing in the slide show demonstrating the setup for testing these guns.

Results of tests not only ruled out iron for series production, given the fragility of the foundry techniques of the time, but also indicated the light bronze guns were unsuitable.  But for sake of economy, the Army didn’t want to maintain a wide variety of gun carriages for short and long 6-pdrs.  But consider Poinsett’s point of view in this.  At the same time he proposed centralization of the Army and sweeping changes to the militia.  So complete re-equipment of the field batteries was likely part of the agenda.

And Poinsett didn’t hold back in his letter to the Ordnance Board in March 1840, stating that he was …

… not satisfied that the corps, collectively or individually, posses that practical knowledge which the importance of the subject, both to the country and the reputation of the corps, would seem to require.  He [Poinsett] repeats, therefore, his wish that this desirable knowledge should be acquired with as little delay as practicable, and for that purpose that the three junior members of the board should proceed to Europe, accompanied by a practical founder.

Also in 1840, Poinsett approved purchases of European guns for testing.  At the same time, West Point provided two iron guns for comparison tests against the European guns in 1841.  The guns had an 11 inch base ring, measured 66 inches in length, and weighed 849 pounds.  Some sources indicate a gun presently in Fredericksburg, Virginia may be one of those guns tested in 1841.

Fredericksburg 19 Feb 11 066
Unknown Iron 6-pdr at Fredericksburg

Cited as “Old Sam Tilden,” it lacks any identification marks, and I have my doubts.  But the form matches the final approved Model of 1841, except in iron instead of bronze.  (Perhaps the folks over at Mysteries and Conundrums might shed light on the history of this gun during their continuing research.)

Setting aside the pedigree of “Old Sam Tilden” for the time being, none of these tests swayed Poinsett. Iron was out for field pieces.  At Poinsett’s insistence, and even before the 1841 tests, the Ordnance Board completed the redesign of the bronze 6-pdrs.  The first of the new model bronze guns passed inspection at about the same time as the comparison gun tests of 1841.

The new gun was a weapon fully 15.7 calibers (nearly 66 inches overall) in length, with a large base ring of 10.3 inch diameter.  It weighed 880 pounds, exceeding all previous standard service guns in the caliber.  Before leaving office, Poinsett put in motion plans for quantity production of the type.  I’ll turn next to the particulars and history of the Model 1841 6-pdr Field Gun, which helped win the Mexican War, figured prominently in the early stages of the Civil War, and is of course rather familiar to battlefield stompers today.


Aside from on site notes and links provided above, sources consulted for this post were:

Birkhimer, William, Historical Sketch of the Organization, Administration, Material and Tactics of the Artillery, United States Army.  Washington:  James J. Chapman, 1884.  Particularly pages 275-9 discussing the evolution of the American systems of artillery.

Hazlett, James C., Edwin Olmstead, and M. Hume Parks. Field Artillery Weapons of the Civil War, Revised Edition. Urbana and Chicago: University of Illinois Press, 2004.

Olmstead, Edwin, Wayne E. Stark, and Spencer C. Tucker. The Big Guns: Civil War Siege, Seacoast and Naval Cannon. Alexandria Bay, NY: Museum Restoration Service, 1997.

Ripley, Warren. Artillery and Ammunition of the Civil War, 4th Edition. Charleston, S.C.: The Battery Press, 1984.


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