/k/ - Weapons

It's much easier to make a smoothbore shotgun

>>619484

what if i want to make an actual centerfire gun?

>>619478

Start with bar stock.

Use a drill bit welded to a drill rod.

Use a lathe to drill through.

The use a button to cut rifling.

https://www.youtube.com/watch?v=gtLYnqZQHCY

>>619487

You'd need to know enough about lathes to invert the threading gears. The fastest I've seen a factory lathe go to is one turn in four inches, much too fast for even a .308.

>>619503

There are three ways that rifling is cut.

Button rifling is done be swaging or broaching out the barrel with a "button."

Hammer forged barrels are hammered with a special machine over a mandrel.

Machine cut rifling is done on a special machine that holds a tool bit and pushed through at a controlled twist rate.

All three are shown on youtube vids and easily found.

Button is the easiest way for a home shop hobbiest to make a rifled barrel without spending a small fortune.

You'll have to get round stock and drill it, ream it, and then you can button rifle it. Rifling buttons can be had on eBay shipped out of China in most any sort for a decent price and can be used many times. No idea what needs to be done in terms of heat treat/stress relief though I've never messed with it that far.

>>619508

how do i drill out a round without the drill bit wondering and going completely off? the guy in this video >>619491 had the exact same problem

>>619509

>>619508

i'm trying to do this without having to use a lathe

>>619509

Use a lathe and do it in stages.

Do some googling and watch some youtube vids on the subject.

>>619510

You could bore your initial hole with a drill press and then just shove a rifled liner in. Even if your hole isn't perfectly straight you can adjust your sights to account for it so long as where the bullet ends up is consistent.

>>619514

This is a recipe for disaster.

Lined barrels have been tried before.

A moderate pressure cartridge (9mm for example) can blow the liner out the muzzle.

>>619510

Ha, you're fucked. In fact good luck making anything gun related without a lathe.

>>619515

Not sure how it differs all that significantly from the two-piece barrels currently being used on .357 revolvers.

>>619519

The two piece barrels are essentially a full on barrel that have an external sleeve.

It is not a liner as such that the inner barrel is where all the load baring structure is.

>>619509

By clamping it tightly and start by drilling a smaller diameter hole and keep making it larger so you can correct the hole if it wanders. If I had to do it by hand I'd drill both sides of it with a very thin drill bit and work my way up to the proper size.

The important question that everybody is ignoring is where to get proper steel for a barrel without going to a metal supply place and getting rod stock there. Is there a cheap substitute you could find in a junk yard or as a replacement part or as a piece of something that's widely sold everywhere?

>>619518

what the least expensive lathe would you recommend then?

>>619529

there is a car yard near where i live, i hear the metal in car axles is strong enough to be used as a barrel

>>619529

>>619532

Beam axle off a large truck. A lot of it is SAE 10XX series which may or may not be usable. If it is 1018 go ahead, but 1050 is pretty common and not as suited for the task. Some heavy equipment uses 4140 in which case you've hit the jackpot.

>>619534

>1050 is pretty common and not as suited for the task

could i just pick an axle with a larger diameter to compensate?

>>619540

This comment alone proves you are retarded. Take up a machine shop class for a year and then try.

>>619546

>This comment alone proves you are retarded.

How? a round with a larger diameter should be able to resist pressure and shock better than a smaller diameter despite it being the less ideal grade of steel, the reason why gun manufacturers don't do this all the time is because it adds weight and costs more material wise than just easily sourcing a more ideal grade.

>Take up a machine shop class for a year and then try.

You see, that would be helpful if i was actually asking a question related to machining.

>>619549

Go make a barrel out of 50mm of BMS if this is your call. I guarantee it won't end in disaster.

On the topic of lathes, I'm no "fuck yeah science" kind of guy, but lathes are pretty fucking awesome.

>>619549

> a round with a larger diameter should be able to resist pressure and shock better

Buddy, rounds don't spontaneously combust when you will them to fire. See, there's this thing called a primer…

>>619564

no, i'm talking about a round bar not a bullet

It's easier to cut rifling in a pipe that's already made, but if you want to go the hard way here you go:

https://www.amazon.com/s/ref=nb_sb_ss_i_10_12?url=search-alias%3Daps&field-keywords=steel+dowel+rod

https://www.amazon.com/s/ref=nb_sb_ss_i_10_12?url=search-alias%3Daps&field-keywords=steel+rod

The magic words are "steel dowel rod" or "steel rod"

>>619510

THEN USE A BUTTON METHOD ON THIS

https://www.amazon.com/Online-Metal-Supply-Steel-Mechanical/dp/B072BXJXXZ/ref=sr_1_17?s=industrial&ie=UTF8&qid=1540602025&sr=1-17&keywords=Metal+Tubing

Fucks sake if I cared about gun making I'd read every post, not every 10th.

>>619509

You are asking a big question there. Modifying the internals of a pipe is one of the greatest challenges of machining.

There are some smart solutions, but oldschool is cooler than all of the new ones.

Get two bars of steel, one already rifled on the outside and with the diameter of your caliber (Rather difficult to produce, but it's possible. Use a very heat resistant and hard metal. It's called a mandrel.), and one bar of steel of the kind you want to use for your barrel.

Heat the future barrel to a point where it can be worked on. put the barrel-negative below the bar and beat it with a hammer so the future barrel folds around the barrel negative. Keep doing this until you get to a point where the two ends of the future barrel meet.

Heat that area to a point where the metal actually melts to connect the two ends. Let it cool until it's all solid again.

Now heat the entire thing until the barrel expands to a point where you can remove the mandrel.

Now you need to heat-treat the barrel and you are set.

>>619529

High quality screws and bolts. The big ones. You can get them in the perfect diameter and length for pistols and sub-machine-guns, and nobody will bat an eye if you buy 20 or so M30 screws.

>>619478

It's right in your OP pic: use thick medium hardened steel rod, drill bore into it, lathe to a smaller external diameter if necessary. There is no special fuckery involved in making gunbarrels, it's just finding exactly right material means you can make it thinner and more lightweight for the same strength.

I never knew rifling buttons were so cheap, a few of those, a bunch of drill rod and a harbor freight hydraulic press and you'd be set for rifling.

>>619979

Steel isn't so hard that you need a hydraulic press, it can be done with a simple drill turning a geared press.

>>620503

>medium carbon steel rod

Can you just *BUY* one-off steel rods?

>>620522

look up 4140 steel bar, or seamless rolled tube of the same grade. you should be able to find a local supplier in the nearest reasonably sized city. failing that they could probably order in a standard length.

>>620522

>>620523

>>619478

https://www.metalsdepot.com/alloy-steel-products/4140-alloy-round-bar

I want to practice rust bluing, what are my best options regarding stock metal?