Building an Action

With these already hardened 41 series, is there any work hardening going on? What are they like after all the machining is completed? I know you sure get work hardening in the annealed state, from machining.
 
Steels

The fact that Remington sells a 300 and 338 Ultramag on a 700 416 Stainless reciever tells you something about how overplayed a lot of this "is it strong enough" thing is.
As for performance, Remington uses their standard 4140 bolt head in their Stainless Actions, the diss-similiar metal contact seems to handle the galling problem quite well.
As a note, B&M Transmissions sells two high performance input shafts for their racing transmissions. One is made from 6418 HY-Tuf, the otherfrom E-4340. The E-4340 version is the strongest, and the most expensive........JACKIE
 
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Leeroy, we need to put some bright light

On this.

At first if you want to use a pre-hardened steel and start with a 50MM (2") bar you have no other option, than to use Thyssen 6580, or Bohler/ASSAB, Atlas EN26, 4340. These materials have to be in X, W, Y heat-treated condition to give you the hardness you need.

Keep in mind, that even the X condition would be only suitable at it's absolute top hardness end and even the W condition is only marginal up to about half of its allowable hardness range.

If you'll use any of the 4140 type material that includes 709M you'll have to heat-treat the material in one way or other, as this type of material will be "too soft" inside where the critical "locking" areas are. The 4140 family hasn't have the same hardenability as the 4340 family has.

The steel needs to be a nickel,chrom/moly type to have the hardness penetration with a "relatively" low carbon (.35-.43) content. The content of the nickel is the crucial element to achieve this.

Far as I know the Tyssen 6580 is no longer imported to Australia and it had a perfect hardness of 39-43HRC. Pity.

Conditions of hardened steels/UTS min. UTS max. in kg/sq.mm HRCmin-max.


X - 108-123kg/sq.mm - 33-38HRC

W - 115-130kg/sq.mm - 36-41HRC

Y - 123- 138kg/sq.mm - 38-43HRC

Z - 155+kg/sq.mm - 47+HRC

As you can see, there are overlaps and as 4Mesh said it's far more common to get the "Lower end" of the range, then is to get the upper end.

I do carry a carbide thread insert on my key ring. I can scratch a piece of steel and estimate the hardness within 3HRC from 30-66HRC. But I have years of practice and I don't expect you to learn that overnight. However if you practice you may be pleasantly surprised, as anything is possible.

I hope, that I was some help to you.

Shoot better
Peter
 
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Leeroy

I tell you what I will do for you, in the interest of "international relations".
Since I am in The Machine Shop Business, I have access to anything I want.
So here is what I will do. I will call one of my major steel supplyers and aquire a piece of Premium Aircraft Quality 4140, and a piece of Premium Aircraft Quality 4340. I can probably get either in 1.5 inch diamter.
I will send it over to Lone Star Heat Treating and get it treated to what ever hardness you desire. I will make sure that they just do not "toss it into the furnace" with a bunch of other stuff..
I will then ship you the material from my shop. You just pay for the Heat Treat and the shipping, as I will probably be able to get the material on a lark, since we purchase thousands of pounds a year from our supplyers.
If you decided you would rather use one of the precipitating hardenning stainless steels for the action body,. I could get a piece of 17-4 or 15-5, have it age hardenned at 1050 degrees F, and do the same deal
Let me know.........jackie
 
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I just need to clear something up. Earlier i stated that 709M is similar to 4340. It is indeed classified as a 4140 and has often been called free machining 4140. The reason it is also often refered to as 4340 is because its actual tensile strength is almost identical to that of 4340. The machine and cutting speeds in lathes or CNCs can be in creased by 33%. Tooling lasts longer and the surface finish is like that of a stainless steel of good qulity.

Jackie has it dead right about this strength of actions thing. Mild or ordanance steels can and have been used in years gone by for rifle actions where critical areas are case or surface hardened. The fact is we use the best steels for wear resistance and more often these days asthetics. The truth is if a case has a total failure, there is no steel that will not come apart like a grenade and the more load, eject or drop ports there is, the more fracture points there are. No steel can contain 85,000 psi when there is a large volume of gas working on a large surface area.
The strongest part of an action needs to be and has to be the case head. In my mind an action should be designed to support and control the barrel first and foremost. Action strength quotes are more for peace of mind.

Tony Z.
 
Great offer Jackie

Its really hard to get stuff here, particularly when you are only an occasional customer.

It took me nearly a month to locate the 17-4 I used for my action.

Rob Carnell
Sydney, australia
 
Decisions Decisions!!

Ok gentlemen there is obviously some varying differences of opinions here as to exactly how strong the steel in an action needs to be. (Of course in this forum i totaly expected this):D

Since i have to rely on the knowledge and experience of others and since none of you offering the information will be paying my medical bills if my DIY action explodes i need to know a few benchmarks for action strength.

So can someone tell me with absolute certantity the material and the HRC value that a typical Remington 700 receiver and bolt are?

If i then choose a steel thats at least as strong as this then i (and my medical insurance company:D) have nothing to worrie about.

Jackie, firstly thank you very much for your generouse offer. We have a saying here in OZ.. "You bloody legend mate!" :D However as i have yet to realy make contact with the steel suppliers or heat treaters i will not accept your offer just yet. I spoke to my Boss today and have no problems in getting what ever steel is needed (4140, 4340, EN26. allthough only in the "V" condition 31-38 HRC and all are "Preimum" quality.

If i was to use EN26, rough bored my 1.5" dia bar stock and rough turned my bolt and then had them both heat treated to 42 HRC, this gives 1275 MPA UTS and 1000 MPA YTS and good machinability to do the finish machine work.
If a steel with 1275 MPA tensile strength will do the job then i don't see the need to go for a 1500-1650 MPA steel with a 48 HRC and more difficulty in machining in the "as Hardened" state.
I finish work early tomorrow and will start maiing some phone calls..


Cheers
Leeroy
 
Leeroy

I have been told that the bolt heads, (the part that is attached to the rest of the bolt body and carries the pressure), are manufactured from 4140, or a alloy that is very similiar.
I had one tested a few years back, out of a 40x. It was 34 HRC.The Test was done between the luggs.......JACKIE
 
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A different priority

I just need to clear something up. Earlier i stated that 709M is similar to 4340. It is indeed classified as a 4140 and has often been called free machining 4140. The reason it is also often refered to as 4340 is because its actual tensile strength is almost identical to that of 4340. The machine and cutting speeds in lathes or CNCs can be in creased by 33%. Tooling lasts longer and the surface finish is like that of a stainless steel of good qulity.

No steel can contain 85,000 psi when there is a large volume of gas working on a large surface area.
The strongest part of an action needs to be and has to be the case head. In my mind an action should be designed to support and control the barrel first and foremost. Action strength quotes are more for peace of mind.

Tony Z.
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709M mechanical properties are close with the 4340, but only up to an U and maybe at the bottom/middle end of the V condition. U=28-33HRC, V=32-36HRC. Unless some type of additional surface treatment, this is far too soft.

If the action is strong and (over engineered) well designed made of the "best steel" and with two relatively large holes drilled on each side of the bolthead/case and 2-3 holes drilled in the bolt body it would have a very good chance. If a action is made of a "every day" crap material there is probably no hope.

Personally, if I'm going to shoot the rifle, the action strength would be my first and foremost. If it will support and control the barrel that would give me a nice peace of mind.

But, who 'm I to make a comment?

Shoot better
Peter
 
Leeroy-while hunting for steel

I would also recomend to try Atlas steels, if they're still in Australia.

They use to have 6580, 6582, EN26, 4340. The 6580 and the 6582 are both superior to the 4340 and they both vere available in the X,W condition in sizes of 40MM and under.

Shoot better
Peter
 
Leeroy

As another note, Ruger, who knows a little about Firearm Design and the requirements entailed, have been manufacturing their actions from investment castings for some time now. They also offer these cast actions in the largest and highest intensity Factory Chamberings, such as the Ultramags.
The Farley Benchrest Actions that I use are also cast fron 17-4 ph Stainless. I believe Jim uses the lost wax ceramic mold proccess........jackie
 
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The current M70 Winchester (or those produced before they were discontinued) are castings. So is the Montana Rifleman receivers.
Doesn't Ruger make a BIG action for Rigby sized cases, too?
 
Avaliable steels

I did some ringing arround today to all of the majior steel suppliers..

Bohler didn't have any of the v-136 Hy-tuf in stock (I could only get 150mm Dia:eek:). The guy i spoke to was well known to my boss as being very knowledgable but had never heard of thyssen 6580 or 6582.
He also sudgested a W302 tool steel but this is clearly not the way to go.
Atlas steels unfortunatly went out of the steel buisness 8 months ago.

Interlloy can supply 4140, 4340 and EN26 in prehardned "V" condition 31-38 HRC. I asked them about the "Preimium Aircraft grade" and the guy said that all there steel is from europe and is "Preimium" grade. They can supply test certs etc.

As for the heat treatment i phoned a heat treatment mob in west Brisbane and they will heat treat EN26 to any hardness i specify. They hardness test after heat treatment and could supply test certs and garentee a propper job.

I did some more research last night and found several companys in the us making after market actions. Most actions are made from aircraft grade 4340 and bolts from 4140.
In saying that if i design a beefy action from EN26 at say 40 HRC and have the bolt treated to 44 HRC this will still give good machinability in as hardened state and help prevent galling and should be MORE than strong enough for my choice of calibre, .308W at the biggest.

Finial opinions?


Cheers
Leeroy
 
Final opinion

I did some ringing arround today to all of the majior steel suppliers..

The guy i spoke to was well known to my boss as being very knowledgable but had never heard of thyssen 6580 or 6582.
As for the heat treatment i phoned a heat treatment mob in west Brisbane and they will heat treat EN26 to any hardness i specify. They hardness test after heat treatment and could supply test certs and garentee a propper job.


In saying that if i design a beefy action from EN26 at say 40 HRC and have the bolt treated to 44 HRC this will still give good machinability in as hardened state and help prevent galling and should be MORE than strong enough for my choice of calibre, .308W at the biggest.

Finial opinions?


Cheers
Leeroy
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Leeroy

My only question about this "very knowledgeable" guy would be; What does he really know if he doesn't even know who and what material he is competing against with his Bohler V155?

To offer you W302 which is H13 hot work tool steel it tels me nothing, but an ignorance on his behalf. Bohler has far better materials than W302.

You may call him a "very knowledgeable", I personally would call him an imbecile.

Your choice of the EN26 material is good. If you get the hardness from the heat-treaters it will be a very good start.

Accepted International Motor Industry Standard is 38-42HRC. Personally I would keep the hardness in this time and time proven range. However it's up to you to know what you'r happy with.

If it will be "more than strong enough" it deppends on how well you designe and execute the action. At least the EN26 material shouldn't be a problem.

Also keep in mind, that any welding of EN26 is not a very smart thing to do.

Shoot better
Peter
 
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Hardness

Peter, if you think i should keep to less than 42 HRC then thats what i'll do.

I would like to get at least 3-4 points difference in Hardness between bolt and receiver so will probably go for 39 HRC for the receiver and 43 HRC for the bolt. Or should i go the other way arround and make the action harder?
Either way I think thats a pretty good compromise..

If i copy the sizes and sections on my rem 700 receiver and bolt and stick to good common machining practices i don't see any real problems..

And of course you are right, structural welding on most hi tensile steel is (without specific methods and pre/post heat) is a very unwize thing to do.

Cheers
Leeroy
 
Action Building

Leeroy,
I have built three actions, HT them and done all the machine work. Everything that's been posted is right on track, copy the infamous Remington and you can't go wrong. I've put thousands of round through two of mine, it's all good. The other sits in the safe, just no interest in it right now. I researched all of the hardnesses I could find for many book and just used what's been done as a guideline.
Good Luck and enjoy,
Rory
 
Bolt harder than the receiver

Peter, if you think i should keep to less than 42 HRC then thats what i'll do.

I would like to get at least 3-4 points difference in Hardness between bolt and receiver so will probably go for 39 HRC for the receiver and 43 HRC for the bolt. Or should i go the other way arround and make the action harder?
Either way I think thats a pretty good compromise..

.

Cheers
Leeroy
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Leeroy

My reason for having the bolt harder than the receiver is based on a simple logic of toughness. The slightly softer material of the receiver "theoretically" will be tougher then the harder material of the bolt.

For a safety reason in the case of a cartridge case head failure the "extra" toughness of the receiver may suddenly become very handy.

Also keep in mind, that the "specified hardness" of 39-43HRC most likely will be slightly different. This is mostly due to the chemical % variations in the steel, the exact quench and tempering temperatures. Also how the HRC Testing machine is calibrated. I personally re-calibrate mine every time prior I use it for testing of anything of an importance.

The International Motor Industry Standard is 38-42HRC. The reasons for this is, that in this particular range of hardness there will be least % of distortion and the material will also make the best compromise between the strength and the toughness.

In your case of like 39-43HRC there is no concern to worry about it, as long as it's 39-43HRC and their HRC Testing equipment is properly calibrated.

The EN26 has .45% of carbon and there shouldn't be galling present even at 38-39HRC.

The mechanical properties of the EN26 are such, that if you keep the receiver at/or below 40HRC and the bolt at/or below 43HRC. you should be safe in every aspect where the material is concern.

Shoot better
Peter
 
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Leeroy

The biggest problem with welding on any alloy steel that is already hardenned and tempered is the metal exposed to the weld puddle is heated to a temperature way beyong the transformation range of the steel.. In other words, it no longer poccesses the properties as the rest of the steel.
Not to mention Hydrogen Imbrittlement, alloy separation, and a few other maladies that can occur.
Most common alloys can be successfully welded, (except the ones that have additives to instill a true free machining characteristic), if you follow certain procedures. This procedure will vary with the alloy that is being welded.
I like one of the descriptions in one of my steel books. It refers to a material called "sressproof', which is a high carbon high sulphur steel that has pretty good properties with a good machine rate. (it's impact, though, is in the toilet). When the book refers to "weldability", it says, "can be welded, if not much is expected"........jackie
 
Leeroy I'm curious about

Few things.

How do you plan to attach the bolt handle to the EN26?

Are you going to keep the "Remington bolt nose" and modify the Sako type extractor to operate within the diameter of the "nose", or are you going for a "flat/cone bolt face"?

What's the main reason, that you'r going for the Sako type extractor?

If you're going to heat-treat the action/bolt you may also go for an annealed material to start with. One less operation for the heat-treatment to go wrong.

For your sake I hope, that you're not just going to copy a Remington action/bolt, but going to improve on the designe as well.

The "heels" of the locking lugs running into a 2mm wide "joined double radius" groove in the bolt body and the receiver thread running into a radius groove not exceeding the "large thread diameter" would also greatly improve the strength of the original (sharp corner type) designe.

Also an offset larger diameter starting material of bolt could be a very good idea to form a "base/root" of the bolt handle to serve as a one piece bolt solid safety lug and have the rest of the bolt handle added/attached on to it.

Shoot well
Peter
 
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Still deciding..

G'day Peter

At this stage i plan to braze or silver solder the bolt hande on ALA remington style. As stated by jackie it could just as easily be tig welded on. I am very capable at both processes so the design of the bolt will infleuence my decision. Tig welding if done corectly will minimise the heat affected zone, but can cause hard/brittle spots. Brazing/silver soldering would have the effect of anealing the steel if left to air cool, not good for the cocking helix.

As for the extractor this is one area i'm worried about.
It has been stated here pleanty of times that sako extractors are potentialy unsafe in a remington receiver and given the arguments i totaly agree. However i do like the extra reliability and function of the sako extractor. If i do fit the sako extractor some means of covering/pluging up the lug race way will be incorporated into the design.
I will also have a closer look at the maching involved to fit the Remington extractor clip inside the bolt nose. If it's easy enough to do then i'll happily fit a remington extractor. Again as i start to get the mouse into gear in Autocad i'll have a much better idea.
BTW can anyone tell me the advantages of a coned bolt nose?

Of course you are right about the machining. All 90 deg shoulders will have a small radius. Sharp corners are a real "NO NO" in applications like this.
At this stage plan to use the CNC lathe at work to do the threading so no problems in having a thread stop groove with radiused bottem. Even if done on a manual lathe this is still no problem.

I also would like to fit a sako style manual ejector as i don't like the way that the plunger type flickes the case mouth into the side of the receiver on extraction (dented case mouths are the result). The sako type lets the operator controll the ammout of ejection force. Ie you can just have the case flip sideways in the action or you can fling it out 10 feet away.

The action will be designed arround an off the shelf remington bolt so that i can use the bolt i already have if need be.

If anyone want's to chime in here and sudgest improvements, mods to make it better i'm all ears.. Keep in mind that i'm not making a BR action at this stage and realy looking to build something on par with a custom sporter/vaminter action. Something similar to the Borden Alpine actions.

Cheers

Leeroy
 
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