Who uses the highest tensile strength steel of the barrel makers?

[Ardent]

I have a project that will require an absolute minimum dimension barrel, and want to find a better steel than 4140, 4150’s out there, and I know Lothar Walther uses some better than average steel.

Anything US made folks know of above 4140? Will be down to .125” range wall thicknesses.

Appreciate it.

 

[Kuzuba]

I'm going to post to see what others say but my take on it is that since the tensile strength is directly proportional to hardness, you might be sol. Since the barrel needs to still be reasonably ductile and tough to withstand the force of firing, you wont be able to have a high hardness barrel. Most alloy steels with the same hardness will have more or less the same tensile strength I would think.

That being said, I'm not an engineer and since everything is built with a safety factor in mind, if you can get in touch with someone who can do the math you should be able to calculate the thinnest walled barrel that is safe with standard 416 or 4150 and your given heat treatment. Then you can just have a high quality barrel profiled down to it.

But then again I make knives and weld/fit, I'm not a gunsmith or an engineer

 

[Ardent]

The math fortunately is published public knowledge by CIP,

https://www.cip-bobp.org/homologation/uploads/ciptexts/a-4-1-en.pdf

The challenge isn’t finding the dimensions it’s finding the steel, the Europeans use better than we do in North America. Lothar Walther, as anyone who has chambered one will know, is damn hard steel. It’s probably going to be the choice, and I’ve read some internet banter on what the steel is and if it’s true it’s what I’m after. And it’s not that 4140 won’t do it, it’s simply I have a greater built in safety factor the better the steel, which appeals to me in an ultra thin barrel.

For that matter who is importing Lothar Walther blanks, anyone know? I bought some on here used once, but need a steadier supply than happenstance.

 

[G.E.FLACH]

Have you looked at T630 stainless .A few barrel makers were using it including Lothar Walther for there barrels .You can also nitride a 4140 barrel .Nitrera in Langley can do it for you .I have used them before for hardening Mauser and ZG-47 actions.Barrel has to be completely finished as it will be 60C Rockwell when its done.

 

[Kuzuba]

Well I'm sorry I cant offer any real help then, but I am a bit of a steel geek so I'm going to hang around and see what others say and see if I can learn something.

 

[Blastattack]

A barrel made from 17-4 and then hardened would be the ticket.

 

[Ardent]

Have you looked at T630 stainless .A few barrel makers were using it including Lothar Walther for there barrels .You can also nitride a 4140 barrel .Nitrex in Langley can do it for you .I have used them before for hardening Mauser and ZG-47 actions.Barrel has to be completely finished as it will be 60C Rockwell when its done.

Really appreciate that lead Gary on Nitrex.

I’ve been avoiding the stainless steels as I’d have to solder these barrels as they’d be for a tiny double. Definitely can be done I just have no experience at it. Same reason I haven’t looked at nitriding yet, thought depending on the process temp I should really consider that for the finished barrels if silver soldered. Would be neat actually.

 

[G.E.FLACH]

Company name is Nitrera not nitrex.They are firearms knowledge based and licenced.
Process of nitriding is around 1100 'F.
Would not want to have to regulate with silver solder.
Sorry for the messing up the name.

 

[just having some fun]

if you are going for a thin barrel/ chamber .. have you thought will the thickness you are going to use ... will it pass a proof load test ?

 

[Ardent]

Yes.

And sounds good Gary, me neither but I’ll try anything once. Would love it to be weather resistant.

 

[leelad]

Steel is a crazy world and metallurgy is a field all in itself(a field I do NOT major in, but one that fascinates me). As you're aware, "hardness", "tensile strength" and "toughness" are not the same things. Hardness may well improve resistance to wear but it will not improve structural integrity. In fact, for a given alloy, as hardness increases, toughness decreases. Now nitrating or similar processes only affect the exposed surface (much like case hardening) and therefore leave the substrate material alone(ie tough). But if you're after a superior material, then that is what you have to start with.

As my boss used to say, "4140 is pretty darn good stuff". And it is. with a tensile strength of 98-125k psi depending on condition it is a standard by which many steels are compared.

17-4 stainless is awesome stuff. Depending on the condition, it can have similar tensile strengths to 4140 and is orders of magnitude superior to 416ss with its(416's) tensile strength of 75-85k psi.

4340 is mucher heavier dutier stuff, having a tensile strength of up to 165k psi. Generally we use this when 4140 wont quite do the trick.

There are many many other options out there of course, but these are a sampling of commonly referenced alloys.

If you aren't able to find Lothar Walther blanks or another "off the shelf" solution, I will soon be able to make barrels out of pretty well any alloy you wish. My rifling machine is 90% finished (my electrician is currently wiring it up and I hope to be able to start motion testing in the next week or so). I may sound forward/arrogant, but I'm honestly not someone to make claims I can't make good on. If you want something built that is out of the norm, I am very confident I could help make it happen.
Your project is one that interests me, I'd be willing to make a few test barrels with you and see how thin/hot they can be pushed before failure... feel free to shoot me a pm if you're interested.

Regards,
Paul.

 

[BattleRife]

For ultimate strength with outstanding toughness, 4340 is the ticket.

If you want to go all out, look for a specialized grade of 4340 known as 300M. It is typically sold as a special bar quality stock, so getting a size that can be made into a barrel shouldn't be too difficult. Most commonly used for things like F-18 tailhooks, so source from folks who routinely supply the aerospace industry. Expensive to buy, probably tough as hell to work, and with a very persnickety double heat treatment to get the desired properties, but it can legitimately be brought to a 300 ksi (2.0 GPa) tensile strength.

 

[G.E.FLACH]

You have to be able to machine it .T630 or 17-4 work hardens ,machines ok but 4340 just wants to tear .4350 machines nice and has some strength benefits but nitriding surpasses all of them .You add the outer and inner layer of hardness trumps them all.I believe it to be around 010 depth at 60C Rockwell and it comes out a nice satin black color.I have just gunkoted right over top of the Nitriding as they blast the metal with 120 grit alox before the process.Just ask them not to beat blast after they are done .

 

[cosmic]

I recall doing the hoop stress calculation for a rifle barrel many years ago, and was surprised to find that the stresses were much lower than I expected. (ie well under the endurance limit). This is particularly true as one progresses from the chamber to the muzzle, owing the the fact that the pressure reduces from (say) 60,000 psi to (say) 10,000 psi.
So, if you want to save weight, one might consider:
1) NDE examination of the barrel. This would allow you to operate closer to the endurance limit. This is standard practice in many industries. (Perhaps this is already done in the barrel manufacturing process, dont know?)
2) Recognizing that the stresses attenuate substantially through the barrel length, perhaps the barrel taper could be more pronounced than the standard sporter profile.

 

[Ardent]

Not the first very thin barrels I’ve included in projects, North American conventions on barrels are extremely, extremely heavy. My .375 Kemano is only .100” at the muzzle, and I own / have owned doubles in .375 Mag the same.

I read a repost of a test a fellow did where he kept turning down a .30-06 chamber until it failed, firing it with a string and tied into a tire. Chamber didn’t burst until he was in the .060s, or ~15 sheets of paper thickness.

CIP with the highest quality steel lists a minimum chamber wall for .223 (and my little wildcat) not far off the muzzle thickness of my .375. I’d like to be able to be well over the minimum, even under the monoblock of this little double, the best steels will allow this but 4140 is borderline and I could be forced to accept lower pressures. I probably will load it moderately anyhow, but it’s sure nice to have more options and safety factor for nothing but better steel.

Gary’s dead right it has to be easy machining, as I’ll be turning down the blanks to become barrel liner thickness, even less. That’s a lot of turning for a hard machining or troublesome alloy. This said something a little harder won’t be unwelcome to resist that thin tube whipping.

 

[Ardent]

This is the recent .375 build, this .358 will need barrels the same sorts of dimensions, except I’ll be narrower where it counts at the chamber ends than I was able to be with this .375. Hence the search for better barrels.

 

[Dogfish858]

The muzzle of the Böhler barrel on my Anschutz .375 is quite close to yours. My thinking is that Böhler, Lothar Walther, vintage German DWM, Carl Gustaf use a high nickel high chrome steel based on ores that were easily accessible (iirc mined in Sweden) though likely now specific formulation. You may find that reboring a couple vintage 8mm German barrels or better yet 6.5 swede gives you your required steel.


Or contact Böhler as they have a Canadian division.

 

[nowarningshot]

Can't wait to see the finished product.

 

[cooperod]

But what kind of accuracy are you able to achieve on a thin barrel like that? Are they hard to tune a round for?

 

[Ardent]

Not at all, that .375 is amongst my best shooting hunting rifles. They heat up quicker, but it shoots as well as my heavier barrels for the first two, and the third starts to walk but only a smidge. Numbers 4 and 5 start to get more spirited in their wanderings and downrange explorations. Frankly though, haven’t shot at a animal alive that wouldn’t have been a clean kill if I fired the first three in the air, then the fourth at it with that barrel. If I’m ever firing ten shot groups at the range I have to give up shooting, as the reason I’m into the guns is gone; hunting. And for hunting, the lighter the sweeter in my version of it.

I don’t do the range except for practice or load development, and it’s off a backpack usually there or offhand as when hunting. I shoot the lighter rifles that handle sweetly the best in those scenarios, anyhow. As for load development it’s liked every bullet I’ve tried with it (235gr Speer, 235gr TSX, 230gr CEB, 260gr Accubond, 200gr CEB). Lots of the European rifles, even the Zastavas in 9.3 and above, are equally slender.