Dan - I am guessing you are refering to brass as to yield strength. If I remember right, Gun bronze yield strength far exceeds mild steel. Your estimate is probably right on (for brass), Just clarifying. We all need a Marks Handbook or Mechanical Engineers book handy, don't we.......................Lynn
There is a considerable difference in "tensile" and "yield" numbers. Numbers from one place to another tend to vary somewhat for similar alloys and the way these alloys were actually formed into the shape being discussed.
So far as far exceeding mild steel it will depend on many factors. Cold rolled 1018 is "stronger" than hot rolled but is far less suitable for shock applications.
So the strongest material might not always the best for a firearms barrel. There are many other factors to consider. The bronze guns had a better record in Civil War Artillery than iron for several reasons. The biggest was in how the metal handled heat. In battle with panic level firing rates the iron guns got very hot and it was thought at the time that the wet mop was damaging the tubes and causing them to burst at some subsequent shot. The bronze guns with their better conductivity did not seem to be damaged by this.
If I were making a "brass" barreled gun I would try to find a alloy identical to the bronze used in military artillery of the mid-19th century. Even small additions of other material can change properties of the material.
Dan
Below is from
http://www.atlasbronze.com/C46400_product_sheet.html?gclid=CO74xJn30ZUCFQ77iAodO3RTiQand gives somewhat higher numbers than the other reference. Also note that it is noted as suitable for use for "pressure vessels". But again this is not necessarily the same as a firearms barrel since pressure does not mean there is any shock loading of the vessel.
Material:Copper Alloy Number 464 -- Wrought Naval Brass, Non-Leaded Naval Bronze, CDA 464
Naval Brass or C46400 is a high strength, corrosion resistant alloy containing nominally 60% copper, .75% tin and 39.25% zinc. It is widely used in marine construction where a strong, corrosive resistant and hard material is required. It is available at a comparatively low cost.
Applications:
Marine: Propeller Shafts, Marine Hardware, Decorative Fittings, Shafting, Propeller Shafts, Turn buckles.
Industrial: Welding Rod, Condenser Plates, Structural Uses, Valve Stems, Balls, Heat Exchanger Tube, Aircraft Turn buckle Barrels, Bearings, Dies, Golf Ball Production, Pressure Vessels, Bearings, Bushings, Hub Cones
Tensile Strength: Minimum 55 ksi
Yield Strength:Minimum 25 ksi - 0.5% Ext. under load
Elongation: 50%
This steel is a mild hot rolled steel (this gives lower tensile and yield than cold rolled)
http://www.onlinemetals.com/alloycat.cfm?alloy=A36&print_this_page=1lists it as ATSM A36. It appears to be 1026 steel, 26 points of carbon.
Ultimate Tensile Strength psi 58000-79000
Yield Strength psi 36300
Elongation 20%