what type/grade of steel is best for cannons?
It's best to buy known grades of steel, not only for confidence in its strength but so you know its characteristics, such as whether it welds easily. 1018/1020 (mild steel) is fine for reproducing barrels of antique guns as it is much stronger than bronze or cast iron and less brittle than cast iron. Higher strength alloy steels like 4130/4140/4150 allow less material in the design but that should only be taken advantage of if you are engineering the design versus simply copying an old design. Most ordinary stainless steels are less strong than 1018/1020, although if you are duplicating an old design, especially if it was originally cast iron, they should be strong enough.
The mild steels weld easily; the alloy steels require much more special handling when welding. Most non-hardening stainless steels weld well.
