Hmmm, Reynolds-953, interesting.... reminds me of the Excell tubing used at Steelman.
What do you mean by "tough"? How do you measure it? Note that stainless has more alloy varieties than just about all other structural metals. It is used extensively in industrial applications, oil-refineries, food-processing, submarines, nuclear reactors not to mention in my favorite gun the
Desert Eagle. Here's some standard properties of various materials:
Chromoly-4130, annealed
density: 0.284 lb/in^3
ultimate-strength: 81.2 kpsi
yield-strength: 52.2 kpsi
elongation@break: 28.2%
modulus elasticity: 29.7 kpsi
Titanium 3Al-2.5V, annealed
density: 0.162 lb/in^3
ultimate-strength: 89.9 kpsi
yield-strength: 72.5 kpsi
elongation@break: 15%
modulus elasticity: 14.5 kpsi
Titanium 6Al-4V, annealed
density: 0.162 lb/in^3
ultimate-strength: 120 kpsi
yield-strength: 110 kpsi
elongation@break: 12%
modulus elasticity: 15 kpsi
stainless-321, annealed
density: 0.289 lb/in^3
ultimate-strength: 95 kpsi
yield-strength: 60 kpsi
elongation@break: 40%
modulus elasticity: 28.5 kpsi
Gall-Tough+ stainless, annealed
density: 0.275 lb/in^3
ultimate-strength: 232 kpsi
yield-strength: 212 kpsi
elongation@break: 24%
modulus elasticity: 26.8 kpsi