High Pressure Tool Steel

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by 375rifleman, May 21, 2014.

  1. 375rifleman

    375rifleman Well-Known Member

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    Hello I was just wondering why tool steelcartridge cases aren't used more with close to limitless reloading capabilitiesas the 338 Yellow Bastard is the only rifle cartridge that uses tool steelinstead of brass as the material for its cartridge cases? I was also wonderingif tool steel is used for the cartridge case how much higher than SAAMI specscould you go(?) as I want to use a tool steel 308 Winchester / 7.62x51 NATO for use in a FAL with the velocities of a 30-06 or even a 30-378 Weatherby is this possible (?) I do realize it would be like a 308 Winchester +P+++++ (?) could using this type of case take some of the pressure of the action of whatever is firing the round (?) Any answers or thought would be much appreciated.
     
  2. Trickymissfit

    Trickymissfit Well-Known Member

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    I really wanted to avoid this post, but the more I think about it the more I have reservations.

    * tool steel is never ever a good thing to build a cartridge case out of. AS IN NEVER! The case should always be the weak link in the system and designed to fail. Yet I know tool steels a little bit, and cost alone makes the grand scheme insane. Your never going to fire form a case, and are basically a one shot deal.

    * now the phrase tool steel has more than likely taken out of context here. Tool steels come in many forms and most are designed for a single purpose even though they often cross a line here or there. One steel that the uneducated will often call out as tool steel is something like 4140, or 4350. The 4*** series are not tool steels. Then we have various trade names with no numbers attached. Rex 95 and Vasco Supreme come to mind instantly, and these are normally used as cutting tools (also known as High Speed Steel), and are very brittle. Once again not good for a rifle case or action. Yet most folks will simply think generic numbers like O-1 & O-6. I would automatically think of steels like D-2, S-5, and A-2 in my mind. They all have one common core in that they are inflexible, and instead will simply break or crack rather than flex a little bit. Also a no no. We see rifle actions built off of custom alloys in the 4*** series all the time. Why? Strength is there, and flexibility. We take something like a pretreat 4150 or 4350, and hard turn it (turns very well unlike some of the tool steels). Then simply nitride it, or harden the parts we want harden while leaving the rest soft (still 30RC). This process gives us the best of both worlds and makes us safe. Can you make an action out of tool steel? You bet, and I saw five built once (Rem. 700 clones) out of two different alloys (Khetos, and A-2). Three failed shooting Federal .308 ammo), plus they seemed to have harmonic issues like we could only dream of. They cracked at the bridge. One is sitting on a desk top right now and used as a paper weight! Had these two guys used tool steel case in these actions, they might be dead right now.

    If somebody tried to sell me tool steel cartridge cases, I run away from him as fast as I can!
    gary
     
  3. J E Custom

    J E Custom Well-Known Member

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    +1
    I think you summed it up well Gary.

    J E CUSTOM
     
  4. 375rifleman

    375rifleman Well-Known Member

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    Thank you for clearing up my question about using tool steel for cartridge cases gary as you can clealy see I was simply trying to get to much out of a case that was never intended to handle the pressures involved and showed just how little I know about the pressures involved in a gun/cartridge.
     
  5. Trickymissfit

    Trickymissfit Well-Known Member

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    Seriously, I could build you a cartridge case that would easily handle 100K psi, but also send you to the trauma ward. You could never resize it, and cost alone would be unreal. In a rifle, you want the weak link to be much weaker than the action and a planned point of failure. Somewhere along the way an engineer sat down with a calculator and steel manuals figuring out what kind of strength he's built into the action. He's not always looking at what it takes to blow the action up, but probably looking at the yield strength of the steel (or whatever they used). Once a piece of steel surpasses it's yield point, it can never come back to what it was in it's original form. It's like bending a piece of steel in a vise. Another issue is metal fatigue, and how soon the steel is taxed beyond a point that is acceptable. As you fire the rifle under high pressure (lets think of 65K psi) the typical action is moving in several directions at the sametime for a very few milliseconds. Not a lot, but it's moving. The bridge alone expands and then contracts back to the OEM spec. The bolt actually compresses, and the stretches a little bit. Plus a twisting motion is transferred back to the bolt face from the stress created by the bullet striking the lands and grooves. These stresses done over and over fatigues the metal if the forces are too high, and trust me that engineer has the square inches of metal calculated, and will build in a safety factor to keep us alive. Many work on a two to one safety factor and some probably think of four to one. This also is tested from time to time in destructive testing, where they want to blow the action up. A good read on this is from either Bob Greanleaf or maybe M.L. McPherson on how to blow up an action as written in precision Shooting magazine. (believe he seriously blew up a Savage action). The article is an eye opener! A case made of tool steel (lets say something really good like A2 or S5 (S5 would be my pick) would not react well to the constant stretching and compression for starters. The granular structure is virtually inflexible, but also very fine in structure. Strength wise it has it all, but is also a fish out of water. On the otherhand a case made of brass will flex, stretch, and fill the voids of the chamber effortlessly. Yes it's not as strong , but also remember the actions are designed for 70K and less (really 65K and less). Ever break a drill bit while drilling a hole? We all have! That's what the case would be like with 60K psi in it!
    gary