Science: Steel to the Breech

Steel may soon replace brass in U.S. shell casings; and if it does, the substitution will cut by nearly 50% 1942's estimated copper shortage of 770,000 tons.

While conducting their own experiments, Army ordnance officers are intently watching operations at American Fork & Hoe Co. (of Cleveland, Ohio), where steel shells are actually being made for the Canadian Army.

It has been found that some of steel's former disadvantages can be overcome by plating it thinly with copper. This protects the steel from 1) rust, 2) damage by powder fumes, which corrode unplated steel casings so badly that they can be used only once, though brass casings can be re-used four times. Copperplated steel casings, however, seem to be resistant enough to be re-used 15 times—a great saving even though steel is harder to tool in the first place.

One great advantage of brass casings is that, at detonation, they quickly heat up, expand, seal the gun breech; then they quickly cool, shrink, can easily be ejected. Steel has a slower heat conductivity, a lesser coefficient of expansion, which can probably be somewhat overcome by crafty alloying.

OPM officials are optimistic over the likelihood of substitution, and engineers are already eying Ford's elaborate, automatic machines for making cylinder sleeves. Overnight these can be adapted, with no essential changes, to making 80,000 sleeve-like steel shell casings per day. The Army eyes the whole project with faint, traditional mistrust.