O1 tool steel for muzzle brake?

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partsguy22
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O1 tool steel for muzzle brake?

Post by partsguy22 » Sat Apr 29, 2017 10:11 pm

Is there any reason O1 (hardened and tempered) would make a poor choice vs something like 4140 pre-hard

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fishman
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Re: O1 tool steel for muzzle brake?

Post by fishman » Sun Apr 30, 2017 12:27 pm

Hardened and tempered o1 is tough stuff, a friend of mine made knife for me out of o1. One concern would be machinability. Another would be corrosion, whatever finish you choose would have to stand up to muzzle blasts, raw o1 will tarnish and rust. I keep my knife oiled but that's not really as much of an option here. 17-4 is common in muzzle brakes and only a little stronger, but it's far more corrosion resistant.
Last edited by fishman on Tue May 02, 2017 1:36 pm, edited 1 time in total.
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partsguy22
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Re: O1 tool steel for muzzle brake?

Post by partsguy22 » Sun Apr 30, 2017 4:12 pm

Im making a couple of griffin inspired (87% the size) brakes for my cans and I was just rummaging thru my metal off cuts bin/drawer and saw I had some and started thinking if it would be suitable.

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Re: O1 tool steel for muzzle brake?

Post by garredondojr » Sun Apr 30, 2017 4:35 pm

I was thinking of trying the same. I may try 4340 first as I have some laying around.

partsguy22
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Re: O1 tool steel for muzzle brake?

Post by partsguy22 » Sun Apr 30, 2017 10:49 pm

I tried making one out of a piece of 4140 scrap that I had in my scrap/off cut bin ... :? All I can say is F*** 4140... i can't get a good surface finish to save my life
Well needless to say it went into the recycling bin
The second one (my last small crap of 17-4 ) came out beautifully
Im ordering some 17-4 in the morning

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Re: O1 tool steel for muzzle brake?

Post by yondering » Mon May 01, 2017 1:45 am

I make most of my muzzle devices from O-1, unless I'm using 17-4 to match a stainless barrel. As any intelligent person would do, I machine the O-1 parts in the annealed condition, then heat treat and temper. Final step is to abrasive blast and parkerize. The resulting finish is as corrosion resistant as the chrome-moly barrel, so it's easy to treat both the same way. Annealed O-1 machines nicely and is easy to get a good finish, and the heat treat and temper process is easy in the home shop.

I like O-1 for suppressor mount muzzle devices because of the wear resistance. Just make sure to temper it properly; if you leave it full hard it will crack, a loose prong of a flash hider inside your suppressor isn't a very good mod.

Of course, 17-4 PH is also an excellent material for muzzle devices, and is easy to get a good finish too. I heat treat it in my lead casting pot with a PID controller set to 900F. That works very well, verified by hardness testing at work, 42-43 Rc.

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Re: O1 tool steel for muzzle brake?

Post by cdhknives » Tue May 02, 2017 10:51 am

O1 rusts if you look at it wrong. Great tool steel, but requires extra care in corrosion prevention...much more so than even the average 4140 barrel. It it also tempered in the 400 degree F range, so hard use will soften it too. Granted it is still in the mid 40's Rockwell C at 1000F, but run it red hot once and it's back to annealed state.

I would expect most of the traditional methods of protecting O1 from rust to be unsuitable for a muzzle brake too. Coatings will wear off. nitriding is too high temp...will detemper O1. Oil and grease will burn off. If you are willing treat it like the bore of a cromoly barrel and oil it after every shooting session you will probably be okay. I live in a very humid area and would never touch it for a muzzle brake or flash hider simply from the corrosion issue.
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yondering
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Re: O1 tool steel for muzzle brake?

Post by yondering » Tue May 02, 2017 9:19 pm

Your theoretical concerns are not reality.

The corrosion resistance of parkerized O1 is about the same as the parkerized 4140 barrel it's attached to. No special issues there. If that's a serious concern, you better figure out what to do about the bolt carrier, trigger group, bolt release, and other small parts on your rifle that are also high carbon steel with similar park or phos surface treatments.

"Run it red hot once" Really? You get your barrels red hot? I'm sure it happens all the time playing ninja at the mall. Spring temper for O1 is around 600F, which is a completely acceptable hardness for muzzle devices. If you see your barrel and muzzle device turn blue from heat, it's probably time to ease off on the gravel pit mag dumps.

I'm amazed how many here don't understand using and caring for common tool steels on gun parts. Muzzle devices are not the same as knives, and things that apply to knives do not really apply here.

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Re: O1 tool steel for muzzle brake?

Post by jnjproto » Wed May 03, 2017 1:22 am

Another bit of info. Polished steel will resist rusting much more than a matte or brushed finish.

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fishman
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Re: O1 tool steel for muzzle brake?

Post by fishman » Wed May 03, 2017 10:52 am

yondering wrote:Your theoretical concerns are not reality.

The corrosion resistance of parkerized O1 is about the same as the parkerized 4140 barrel it's attached to..
...
I'm amazed how many here don't understand using and caring for common tool steels on gun parts. Muzzle devices are not the same as knives, and things that apply to knives do not really apply here.
no one here claimed that knives are muzzle breaks, in fact, myself and others claimed that unfinished o1 is good for knives but maybe not good for muzzle breaks so im not sure who you're directing your comment at.

obviously if OP has the ability to parkerize his o1 brake, or have some other suitable finish done, there wont be an issue. myself and others just want to make sure that OP does not pick a metal and finish combination that will not be suitable, as there are many finishes on o1 that would not be suitible for a muzzle brake while a steel like 17-4 requires no finish.
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Re: O1 tool steel for muzzle brake?

Post by cdhknives » Wed May 03, 2017 12:15 pm

I'm sure he is referring to my handle with the knife comment.

Caring for tool steels in the action of a firearm is very different from caring for same in a muzzle brake as most all lubricant type coatings will burn off immediately. Parkerizing works via pores that hold oil...a non starter in a brake as the heat and blast would burn out the oil in very short order from much of the surface. The surface of a barrel is not the same as the surface of a brake exposed to propellant blast at every shot. If it were in my safe it would have to be cleaned and oiled after every firing...hardly a trivial drawback IMO.

And the number of people that run their rifles very hot is not a trivial concern either.
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yondering
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Re: O1 tool steel for muzzle brake?

Post by yondering » Wed May 03, 2017 8:56 pm

cdhknives wrote:I'm sure he is referring to my handle with the knife comment.

Caring for tool steels in the action of a firearm is very different from caring for same in a muzzle brake as most all lubricant type coatings will burn off immediately. Parkerizing works via pores that hold oil...a non starter in a brake as the heat and blast would burn out the oil in very short order from much of the surface. The surface of a barrel is not the same as the surface of a brake exposed to propellant blast at every shot. If it were in my safe it would have to be cleaned and oiled after every firing...hardly a trivial drawback IMO.

And the number of people that run their rifles very hot is not a trivial concern either.
Again, too much theory, not reality. Do you have any A2 flash hiders? No different than O-1 for corrosion resistance. They work fine.
As stated, I make and use a bunch of O-1 muzzle devices, and the concerns expressed here are way overstated. I don't have to treat mine any differently than a standard A2 flash hider.

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