I don't know anything about the "modulus of elasticity" but I worked as a welder for quite a few years and I wouldn't say that SS and CS are equally in rigidity. SS is much more pliable and less likely to have stress fractures on welds when seeing extreme heat. SS also expands significantly more when exposed to extreme heat.
Also, if you have a stainless bar (say 316L for instance) and a CS bar of the same diameter, it will be much easier to bend the SS than the CS one.
I ain't pulling your leg. I was surprised, indeed, a very long time ago to find that the mechanical property 'modulus of elasticity' was the same for stainless and carbon steels.
I could quote you the formulas if you like, but basically the stiffness of any uniform member is related to its length, cross sectional area, and modulus of elasticity. Both steels have a modulus of around 29 or 30 million pounds per square inch. This means that barrels with the same dimensions will be equally stiff whether they are made of carbon or stainless steels.
Stiffness isn't the same as ultimate strength, nor is it the same as machinibility, hardness, or toughness. This stuff gets complicated.
I'm a mechanical engineer, and not a metalurgist. I used to be employed as a mechanical analyst in the aerospace industry. We used 29 or 30 million psi for both steels.
Seriously though, I unless your mel or your sniping people in the military at umpteen billion yards away I doubt most people will notice the difference between SS and carbon. I can tell you however that the R5 (5R?) has an advantage over the standard. Its special barreling is better than the standard. To my understanding it is the same barrel that come on an M24. Rem. only makes them available when there is a surplus, say they made to many for the Army. I am also a little bias because I own one and it is a champ. It is not nearly complete (college = lack of funds), but it shoots unbelievable out of the box. A carbon version could certainly keep up or possibly shoot better I don't know, but in my opinion that would be due to the shooter.
Now the bad news. The barrels on the 5R's are not surplus, they are rejects :shock: Its not as bad as it sounds though. When remington is building the M24's, their barrels have to meet certain production tolerances. If they do not meet those tolerances they are rejected (without being fired). About 5 years ago remington had a bright idea to put those barrels on 700 actions in a 700P stock and call it a "Mil-spec" limited production and sell them for more money. It worked great. But performance is no better, and for the most part, no worse than a standard 700P. Decent rifles, I just do not recommend paying more for a 5R rifle than you would for a 700P.
remington says thier most accurate out of the box product is thier Rem 700 LTR
as far as 5R is concerned... the barrel is GREAT on an M24 SWS but the ones that are rejected could just not have met the requriements by the narrowest of margains and shoot 1/2 moa on a rifle or 3 moa being a POS barrel that should have never been used
though i guess Remington gives a 3 moa guarentee on thier rifles but i'd be shocked if a heavy barreled Remington 700 shot that
guess I got lucky then, mine shoots like a champ and I got it for cheaper that the 700P. The 700P is great and all, but I'd take the standard 700 anyday over the 700P due to costs. A palm swell and an extra mounting lug do not justify the excessive cost.
Maybe I'm a bit too late to weigh in on this, but after reading pcmacd's refution of my claim, I felt the need to defend myself and my training. I'll stand by my original statement that carbon steel is generally stiffer then stainless.
For us engineering types, let's open our ASM handbooks to volume 1 ( or in my case Callister Engineering Materials and Science: an Introduction 5th ed. to appendix B, which copies and references the pertinent ASM values) and we find that plain carbon steels have a listed modulus of elasticity (or Young's modulus if you want to get confusing) of 30e6 or 30 million psi.
Of the listed values for martensitic stainless steels, grade AISI 410 (commonly used in gun barrels, although others may be used) is found to have a published modulus of 29 million psi.
Similar, yes. Identical, no. While the Poison's ratio for all ferretic alloys is assumed to be the same at 0.30, I distinctly remembered that stainless steels were less elastic then plain carbon steels. It turns out that AISI 410 is at the stiff end of stainless alloys. They tend to go downwards from there, ending in the range of 28e6 psi.