Casting Tests: More Experimental 6-pdr Guns

Turning again to the chart of experimental 6-pdrs of the 1830s and 1840s:

The last two lines on the chart are two batches of trials and experimental iron guns from Cyrus Alger in Boston, Massachusetts.  While technically not “field guns” these two batches offer a glimpse of the Ordnance Department’s attempts to determine the best way to handle cast iron.

Perhaps the best place to start the story is in 1840 again, with the commission Secretary Poinsett sent to Europe.  According to the Congressional Report, Major Rufus Lathrop Baker, Captain Alfred Mordecai, Captain Benjamin Huger, and former officer and foundryman William Wade visited Europe in the summer and fall of 1840.  The commission observed foundries in Sweden, England, France, Russia, Prussia, and Belgium.  The men paid special attention to the iron handling in the European foundries.

The commission purchased several guns while visiting Europe.  In reference to the discussion of 6-pdrs, the officers acquired two iron 6-pdrs from Gospel Oak Works near Birmingham, England; four iron 6-pdrs from three different Swedish foundries; two iron and four bronze 6-pdrs from the royal foundry in Liege, Belgium.  All the foreign guns followed the “American pattern” according to the report.  The Army tested these guns, along with two West Point iron guns.  The Swedish guns performed a little better than others during the tests.  But as noted in an earlier post, the Ordnance officers concluded the European iron was not significantly better than American iron.

While bronze was the solution for field guns, the Americans needed iron for the siege and seacoast guns.  Toward that end, William Wade continued experiments focused on the properties of cast iron.  In February 1844, the Army issued a contract to Cyrus Alger to produce four 6-pdrs, each cast under different handling processes:

  • No. 1 – cast directly after the iron was melted.
  • No. 2 – cast after the iron was in fusion for one hour.
  • No. 3 – cast after the iron was in fusion for two hours.
  • No. 4 – cast after the iron was in fusion for three hours.

The pattern used, reproduced here from a diagram in the report, was noteworthy for its lack of adornments, rings, and muzzle swell.

Wade's 6-pdr Trials Guns

Wade reported the guns had the same weight and length as contemporary bronze types, but of course to a different form.  What appears as a “band” on the breech is really a thick reinforce and part of the casting.   As cast, the guns suffered many imperfections.  So Wade rejected those and had another set cast.

For the tests, Wade noted that standard round shot had a tendency to jam up in the bore when used with extreme charges or when stacked on the bore.  So he used a special dumb-bell shaped projectile.  None of the guns lasted past 38 fires:

Although extreme tests, these results were not consistent and not promising. But this did set the maximum proof test at three pounds of powder with sixteen balls.

So Wade tested another four guns.  Again, each handled a bit differently in casting:

  • No. 5 – cast after the iron was in fusion for half an hour.
  • No. 6 – cast after the iron was in fusion for one-and-a-half hours.
  • No. 7 – cast after the iron was in fusion for three hours.
  • No. 8 – cast after the iron was in fusion for three-and-three-quarters hours.

The guns suffered through similar tests.  Wade offered this table of the results:

Of the batch, No. 7 survived the tests. In his summary, Wade offered few conclusions, but did compare the test gun’s endurance with those of European origin tested three years earlier.

Wade continued tests with different castings in April 1844, this time of simple iron bars, at different temperatures and fusion times.  In this report he noted results of tensile strength.  Through the remainder of 1844, Wade continued experiments with heavier iron guns in production at Alger’s foundry and measurements of the specific gravity of the iron.  Late in the year, Wade subjected two old 18-pdr guns and the surviving No. 7 iron 6-pdr to hydrostatic tests to determine breaking points.

Alger continued to produce iron guns for experiments after those two batches.  Registry receipts indicate Wade accepted a ninth iron 6-pdr from Alger in 1844.  Perhaps Wade used that gun in a similar set of tests, but I have found no record of such.   Alger delivered two more iron 6-pdrs in 1848 for testing, likely to the same pattern as the 1844 guns.  A surviving gun, with a 1854 date stamp, at Newport, Rhode Island, produced to a similar form as the 1844 guns is rifled to the James system.  Apparently the “form” was good enough for repeated use.

Granted, these test guns were not intended for the field.  But the results of these tests provided the ordnance officers and cannon foundries with important data on which to build conclusions.  Certainly Wade’s experiments aided later heavy guns that saw service in the Civil War.  But in some small part, experiments with metal handling lead to procedures which gave the Parrott field guns the endurance to handle the pressure of rifled projectiles.

Steps along the way to build a better cannon.