For those who asked earlier, Carpenter 158 is currently about $8-10 per pound in small volumes, if you can find it. It's not really used anymore in mold making because there are fancier powdered metallurgical steels available (the metallurgy in firearms manufacturing is very conservative). On Practical Machinist (a forum for machinists and shops), one of the shops was quoted a 10-ton order at $5/lb for manufacturing these AR-15 bolts to purchase a mill lot. Mills don't just have this stuff sitting on shelves because of low demand, so often you have to buy an entire run's worth and sell the rest you don't use, or sit on it and hope your customer orders more in the future. FYI, Carpenter 158 is a proprietary name for AISI P6, so if you want more information, look up AISI P6 steel specifications. Before it was absorbed by another company in the early 2000's, it was sold by Bethlehem Steel as Duramold-N series.
S7 (AISI S7) tool steel is about $13-15 per pound in small volumes, depending on vendor and finish (mill finish, ground stock, etc) A couple different proprietary names would be Crucible S7 XL, Thyssen S7, Carpenter S7, or Supershock S7.
I use .29lb/in^3 to convert volume to mass given every steel allow varies in mass a little, depending on alloying content. For AR bolts starting from rough sawn 3/4"barstock before heat treat, you're looking at a material value of about $10 per slug. Add about $1-2 per lb with the initial heat treat for toughness, depending on lot size and type. Then machine time. I don't know if AR bolts are case hardened on top of that for surface wear characteristics. A shop with a good turning center and barfeed could crank these out like candy. Another example. Several barrel makers utilize 17-4PH stainless steel as a premium material. We order many tons of the stuff because we OEM for several large abrasive waterjet companies. Their intensifier assembly components operate at 60-90kpsi so it's a similar application as far as repetative pulsed tensile stresses. 17-4PH costs us $2.61/lb. That makes raw material costs for gun barrels about $15 with heat treat if purchased in the same volumes.
What the market will support is the primary determining factor of cost, not the raw material. The markups for premium materials is not linear to the final cost of the product itself. The worst offender of this is titanium products, simply because "titanium". People shouldn't be concerned about what the raw material cost is or what the machine time is, or mark-up. The only factor that really matters would be how the value compares to other products on the market.
Last edited by Cesiumsponge; 06-07-14 at 14:12.
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