What does one need to do to a steel pipe so it can safely be

>>33115091
No it doesnt

>>33115100
Really? I've seen people do this sort of thing and they always heat treat the barrels.

>>33115180
I've actually never seen it done

>>33115180
Buy the highest strength you can, shotguns have much less pressure than rifles. Look up slam fire shotguns on the youtubes. Make sure the barrel is 18.5" so the alphabet doesnt shoot your dog or whatever.

You can also buy a chambered slug barrel for a rem 870 or mossberg 500. They won't be very expensive. There are single shot break action barrels available too that'd probably be even cheaper.

>>33115180
and how exactly did you see them "heat treat" it?

>>33115091
>heat treating

See, here's the thing about heat treating metal. While you are making the material harder, you are also making it more brittle. So when it fails, instead of causing it to warp out of shape, it will shatter like glass. You need to strike the right balance between hardness and malleability. Look up the typical rockwell hardness for barrels (it's not usually that high) and compare it to the material you're working with. For a single-shot shotgun, you might not need to heat treat the barrel at all. Only need to reinforce the chamber.

In any case, I would recommend watching this guy for ideas. He doesn't do such a bad job, aside from the weird firing mechanism.

https://www.youtube.com/watch?v=Bc8nP7CkUpA&t=1353s

>>33115180
I dont see a reason why they would and ive never seen anyone do it. 12ga has less pressure than 22lr and they make 22lr barrels for 3d printed guns with plastic and thinwalled brake line.

>>33115807
Schedule 40 should cover the pressure. Just make sure it is not aluminum and you'll be fine.

>>33115877
He doesnt need to strengthen the chamber. Since when did /k/ get so many people ignorant of slam fire shotguns? A schedule 80 pipe will be fine for the barrel. Another schedule 80 pipe will be fine for the slamming part too.

>>33115091
For a shotgun you won't need heat treat. For a rifle, or really anything above 20kpsi, you will.
>>33115877
>Look up the typical rockwell hardness for barrels (it's not usually that high)
30Rc is still 100% in the quench and temper domain of heat treating.

>>33116026
>For a shotgun you won't need heat treat. For a rifle, or really anything above 20kpsi, you will.

Gun barrels and bolts aren't usually heat treated. You select an appropriate steel and use it in it's annealed form. seamless hydraulic pipe makes for passable improvised gun barrels.

>>33116068
What sort of magic steel are you using that is 30Rc from the mill? Seriously, tell me because I can save my customers millions of dollars and get a big fat fucking bonus for it, for which I'll give you a portion.

>>33116117
What type of "portion" are we talking here?

Keep in mind that heat treating by quench and temper isn't possible on mild steel. Not enough carbon.

Looking at ultimate and tensile strengths listed for some schedule 80 pipe (cursory google) it might mostly be made from mild steel.

>>33116145
I figure I'll get a years salary as a bonus, which is $112k, so how does 10% sound? I mean, if I can save companies like Ford or General Dynamics or Toyota millions of dollars on heat treating when they don't need to be, surely I'll get a nice chunk of change.
>>33116150
No but you can carburize the inside for some nice case hardening. 0.020 case is entirely possible and will go a long way to increase strength without sacrificing ductility.

>>33116150
a proper heat treat involves a long, slow cooling not a quench

we're not talking spring steel here

>>33116150
Schedule 80 steel pipe will hold the pressure of a 12ga. You also have the added strength from the striker sleeve.

>>33116182
Not op but I thought you could get a workable heat treatment by heating to red hot, quenching in oil, then tempering in an oven for 400 degrees for an hour.

>>33115091
Press and pin a sleeve around the echamber for safety.

Also, just buy a fucking barrel blank.....

>>33116177
>>33116182
>>33116184
I'm saying if Schedule 80 is rated to take the stresses that you calculate the shell will produce (with a generous margin of safety), any attempts at heat treatment are at best useless and at worst dangerous.

>>33116199
This sounds true for higher-carbon steels (no idea if the specifics of the process you cited are right).

>>33116199
Something similar was done with civil war cannons using wrought iron, with a heat-shrink fit.
https://en.wikipedia.org/wiki/USS_Princeton_(1843)#The_guns

>>33116199
Depends what you're trying to achieve and your material involved. Heat treat is a pretty exact science.

>>33116224
Yeah, low carbon pipe cannot be heat treated. Which for a slam bang little shotgun is fine, because the pressures are so low. But if you go up in pressures for something like a rifle round, then you absolutely need a higher carbon steel and will need to heat treat.

What about subzero cold hardening?

>>33116232
Ive just watched people make lathe tools and thats what they have done. Unless they specified color like light straw or whatever

Wouldn't guns tend to temper away any hardening to nothing through the heat of firing?

>>33116199
There are many kinds of heat treatments.

Heat and quench will harden many steels. What exactly constitutes a quench varies, for a high carbon steel you'll need somethign like cold oil or water. Other steels will !quench" if you just leave them lying around in room temperature air (these are called air hardening for some strange reason).

Heat and then a sloooow cooling will give you a softer steel instead. It also relives any internal stress from forging or cold working, which can make the item less prone to unexpected failure.

Tempering is a heat treatment on its own, where you remove a small amount of the hardness from quenching, while also getting rid of most of the brittleness.

Now basically every steel alloy responds differently to these things. Some won't harden at all. Some need to be heated more, or less, before quenching. Many need to be kept hot for some amount of time before quenching. Some are extremely sensitive to cooling down between heat and quench. The temperature and time of the tempering afterwards in particular can be a sensitive issue. Too little and your piece will be dangerously brittle, too much and it can leave the steel softer and weaker than before you tried hardening it.

And as heat isn't terribly fast at moving through things, the geometry of the piece also matters.

>>33115091
When you heat that piece of galvanized pipe up to cherry red to "heat treat" it, make sure you breathe in the fumes. They smell so good.

File: 1478659243287.jpg (22KB, 300x309px) Image search: [Google]

22KB, 300x309px

You fucking idiots that always ask this, a fucking barrel blank is as cheap as 30 bucks online. Just do it right and don't take the word of that faggoty YouTube kid who builds ugly guns.
>I promise, you won't blow your hands off doing this
>Promise kiss™

>>33116267
With higher amounts of carbon you need a colder quench to properly harden everything, otherwise you get unhardened spots in there screwing you over. This is part of the reason the temperature you heat to before quenching is so important, a high carbon steel has a lot of carbon locked in carbides, heat too much and they dissolve, pushing up the carbon content of the steel overall to troublesome levels.

(Low carbon steels meanwhile have iron spots in them, if you don't heat enough they won't dissolve, and remain post hardening. We don't mind the carbides in hardened steel, we do mind the pure iron bits.)

At higher carbon contents, this ends up well below zero. At the same time, trying to quench directly to that will result in immense thermal stress, so your piece will probably shatter.

So I guess you kinda need to do a two step quench, first to harden the majority, and then to transform the retained bits in a sub-zero quench, and be bloody quick about it before the remaining high temp style steel decays into normal unhardened steel instead of turning into the hardened stuff.

Now some appear to go for cryo treatment well after the quench. Fuck knows if that's anything but snake oil. Once the atoms have had time to shuffle around a bit the cryo treatment shouldn't be able to do anything at all, it can't make anything move back, as atoms hate moving anywhere when it's cold.

>>33115896
>Since when did /k/ get so many people ignorant of slam fire shotguns?
liberal invasion after trump won

>>33115807
>Make sure the barrel is 18.5" so the alphabet doesnt shoot your dog or whatever.

but because the "firearm" doesnt have a trigger mechanism, and the ATF defines the receiver (which is legally the firearm) as the part that houses the trigger, isnt a slam bang shotgun technically not a firearm?

>>33116316
>Wouldn't guns tend to temper away any hardening to nothing through the heat of firing
No. You'd have to get beyond 900 degrees before you could even start affecting the temper on most firearm parts (assuming 41xx or 40xx steel, which is fairly common). The rest of your post is a good overview though.

>>33116677
>and the ATF defines the receiver (which is legally the firearm) as the part that houses the trigger
No, they don't.

>>33116677
That kind of thinking gets your dog shot. You have to beg the ATF for clarification on every minute detail then keep all relevant copies with your fire arms. I've already had a parts kit taken by the police because my 80% blank was now a firearm.

>>33116117
Sounds like normalised 4140, the same steel used in most barrels.

>>33115091
>the barrel needs heat treating to be strengthened and able to withstand the pressure
it really doesnt

>>33116978
arent the uppers on scars the registered bit?

use sea
mless black pipe, 3/4" nominal diameter unmodified

>>33117036
Yes

>>33117036
>>33117135
Regulated, not registered.

>>33117007
Really? Because all my 4140 gets tempered at 1200-1260 to get 30Rc.

Im planning to make my own shotgun and shells for it, but since im yuropoor i cant just buy smokeless powder for the shells, so im going to use black powder. My question is, if i would use schedule 80 3/4 pipe for the barrel, how big loads would be safe to use?

>>33115091
You cannot heat treat mild steel. Learned this the hard way making knives while not doing the proper research. Pipes are generally mild steel. They're also generally galvanized, which is great for rust, but exposing galvanization to significant heat results in fumes that make you sick as fuck. It's never happened to me, but I've heard horror stories.

>>33116325
Asshole, heated zinc is toxic.

>>33116201
What if it's a survival situation and the ACE hardware has been already looted?

>>33116232
What about coating in kasenite and toss it back into the sword forge powered by propane?

>>33115878
Pressure = Force x Area
12ga is a hell of a lot more surface area then 22lr