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Thread: c;hrome Moly Actions

  1. #1
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    c;hrome Moly Actions

    What are the differences between a chrome Moly vs a stainless steel action? Are there any features to a chrome Moly that make it worth while?

  2. #2
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    Feb 2006
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    145

    Chrome Moly actions

    Chambyrd -

    Howdy !

    The quickest response:

    For whatever reason(s), chrome moly actions are not the " norm " for use in short range benchrest competitions. Perhaps due to all-up rifle wt considerations, where a steel lined aluminum action might provide an edge in wt savings ?

    I have a Wichita WBR1375 single shot benchrest action, that is " plain " steel ". It is S/N 15, and is on it's 4th barrel ( groundhogs and occasional target shoots ).
    I also shot a Wichita " Mini ", which too is " blued " steel. Nothing wrong with them.


    With regards,
    357Mag

  3. #3
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    Feb 2003
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    A slipping and a sliding.

    Chrome moly has more lubricity then stainless. Stainless is more rust resistant. Almost all stainless actions will have a steel bolt that is not stainless and which will rust. Chrome moly actions will often have a stainless bolt. This is because stainless on stainless tends to gall. I suspect that stainless actions are popular because the action is easier to take care of. The bolt, however, must be coated in an anti rust preservative to prevent rust. I have shot stainless, aluminum and chrome moly actions. The choice depends on availability and personal preference.

  4. #4
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    The vast majority of commercial actions, (factory), are machined from some type of chrome moly steel. That being, a variant of 4140. Those that offer stainless usually opt for 416.

    There is a difference in custom actions machined from different stainless steel. It has evolved to where a manufacturer uses either 416 or a precipitation hardening stainless such as 17-4.

    In my opinion, you canít compare these two Stainless Steels. The truth being that all other things being equal, a 416 stainless action will not take the pressures that a action machined from properly heat treated 17-4. Action manufacturers such as BAT use 17-4, and do their own in house heat treating. This makes BAT one of the strongest actions available.

    I have two of the early Farley Actions that are machined from 17-4. In particular, Jim used the lost wax ceramic mold method of casting these action bodies from 17-4. The actions are extremely stiff. Jim also machined his early bolts from S-7 tool steel with a relative high Rockwell C hardness. This gave the actions an ability to take the pressures encountered in Benchrest while having a good anti-gall quality.

    There were a few problems. S-7 tool steel has great strength and impact qualities, but heat treat is extremely critical. To achieve the desired properties, an exact heat and time of heat is measured in very small temperature variations and time. Many of us can remember when Farley had a recall because bolt lugs were cracking. Myself and two friends took ours over to Lone Star Heat Treating and had ours tested. The RC hardness as all over the map. One of mine was on the upper end of what I would call safe, it was 53 RC. Never sent it back to have the temper redrawn, it has had thousands of rounds pas through it with no problems.

    Why donít all action manufacturers use 17-4? The main reason is cost in machinability. 416 at the desired strength level for an action body is much easier on tooling than 17-4. The strength level is adequate for the vast majority of rifle applications. Only in shooting applications where pressures climb into no mans land do you encounter problems, mainly in action stretching, resulting on difficult bolt opening.

    Untill recently, I had an action on my Rail Gun that was machined from 416. My favorite 6PPC loads that shoot so well weíre just about unusable in my Rail Gun because in my Farleys, everything worked great. In the 416 action, a aggravating hard bolt lift was a constant problem with the same loads.

    I solved this problem last year by going to a BAT Neuvo and a 17-4 action. I can now shoot the same upper end loads in both my Bag Guns and my Rail. BAT solves the galling problem by using a Melanite coating on the actions.

    When an action manufacturer touts his actions as being machined from 416, I do not necessarily consider that a plus. An age hardening stainless such as 17-4 would be a better choice if ultimate strength as defined by tensil , yield, and ductility are considered.
    Last edited by jackie schmidt; 12-31-2020 at 09:01 AM.

  5. #5
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    Spot on Jackie. And there's another advantage to using 17-4PH over 416......there's no oil quench when hardening. We switched to 17-4 on our Ruger cylinders years ago. As for our actions, all of them have been out of 4140. For no other reason than it's less prone to galling (that's dad excuse anyways....truth be told, he has a ton of 1.5" 4140 round stock). I did hard-chrome one and it has held-up well (>10,000 rounds through it so far).

    -Lee
    www.singelactions.com

  6. #6
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    Lee, I forgot during my diatribe to say to the OP that if the choice was between chrome moly and 416, I would choose chrome moly.

  7. #7
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    Quote Originally Posted by jackie schmidt View Post
    Lee, I forgot during my diatribe to say to the OP that if the choice was between chrome moly and 416, I would choose chrome moly.
    If one were buying a Bat action, do you feel that a chromoly action offers any advantages over a melonite/nitride finished 17-4 action?

  8. #8
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    Quote Originally Posted by B_Rob85 View Post
    If one were buying a Bat action, do you feel that a chromoly action offers any advantages over a melonite/nitride finished 17-4 action?
    No. That is why BAT rarely offers Chrome Moly Actions. I think they only have an occasional special run of CM.

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