Gunsmithing

If you want a straight channel just go with the largest non-chamber barrel diameter. The paper will add extra diameter to keep the barrel from touching.
If you're going with a tapered channel any size smaller than the minmum diameter of barrel in the stock will work. Little harder to be perfectly even though.

>7.62x39 enfield sporter

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I dont think that will work. You sure you know what your doin? Keep us updated.

Probably an AIA

brownells.com/gunsmith-tools-supplies/stock-work-finishing/stock-making-hand-tools/barrel-channel-cutting-tools/barrel-bedding-tool-prod6796.aspx

>made an action mandrel for my 700
>going to use it to face the action and square up the bolt locking surfaces
>pretty sure I fucked up making the mandrel so now scared I'm going to make things worse instead of better
fuck

thats the shittiest reamer I've ever seen

put it in the lathe and check concentricity

>What are you losers working on?
Your women, she said shes sick of you Fab'in cheap shit and want to blow me for good measure

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Posted this yesterday is /arg/, but pic related is my first attempt at cutting/crowning. It's an 11 degree meme crown done on my shitty HF mini lathe. I'm not a machinist by any stretch of the imagination, but I think I did a pretty decent job considering my lack of experience and crappy tools.

Attached: crown1.jpg (922x692, 133K)

Lathe and mill
It worked great. The front end of a .303 chamber is already very close to correct, it just needs a little bit of material removed
Not an AIA, a beat to shit no1 sporter I got in a trade
Lol u mad

That looks great, nice.

Finished the semi fcg, now i need to weld the reciever and do the semi mods on it.

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Thanks. It was an 18" threaded barrel which is a no no in my state. Cut it down to 16.5" so I can just barely squeeze the rifle in my carbine carry case. Forgot to mention I made a brass pilot to indicate off the bore (I have a 4-jaw chuck) and used a tiny carbide boring bar to make the cuts (from bore outward).

Making slow progress between other projects

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From my understanding of bedding and floating, just sand it out enough that you can slip a dollar bill between the barrel and the stock.
Can't really call it gunsmithing but I'm gathering parts for a New Frontier dedicated PCC based AR pistol in 9mm, perhaps to convert to an SBR in the future, possibly. I've heard the paperwork is always a fucking pain in the ass when leaving town, moving, etc.
Also, finalizing shit with pic related

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This is the same rifle I made the reamer for, first time doing a round sporter style crown.

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What is this? Looks like an ar with no mag well?

youtu.be/ikHT5EtZGqU

Nice. I probably should have rounded the outside edge a little more. Don't feel like chucking it back up though.

Trigger housing for a modular test bed. Kind of like a billet aluminium version of an hk 91/93 using as many standard ar15 parts as possible

I think it's off by like .003

Interdasting.
What are you going to use for the rollers?

I am planning to use axle bearings, but I'm also going to play around with different methods of operation

Wait, are you the guy from CanGen?

Nah. I don't post there

Alright. There's a regular in those threads who is mulling over a not-AK that uses roller delay.

It wouldn't happen to have 4 rollers and be in 45-70 would it

Why cut the D profile into the pilot?

Not as far as I'm aware but that sounds awesome.

it wouldnt be a bad idea considering that most times male bathrooms have artificially created piss lakes under/around the toilet

How did you ensure concentricity with bore?

Show us your setup...

I’m in the process of building a c96 from parts.

I assuming when you cut with EM you cut past halfway and thats how you get your relief. I'm not to sure how this reamer works...

Someone posted some cad drawings to the guild a few months ago. Said they found them on Jow Forums

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Because it's tapered for a lead in as per the saami standards and it make the side cut easier
It's basically exactly in half. Google it. Clickspring did a good video on it.

Furniture is donerino.

Waiting on a few sections of steel rod from mcmastercarr, then work on the stock starts.

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I didn't. Barrel was in the lathe, and I just manually held it, I only had to shave a few thou off the walls behind the shoulder

Looking good

Ive had a long time interest in desiging and making my own firearms but I have no real idea on were to start.

Take some basic machining courses.

Thats sounds like work. But ill do it.

I've started a bunch and never finished mostly from design issues in the action that only pop up from testing and so never get a stock and finish. gunsmithing is actually a very difficult intersection of machining and woodworking. Working on existing guns is a great way to work on the skills you need for the scratch builds. I could have bought a reamer for 150 bucks but I'm cheap and practicing tool making is far more valuable than the modified shit sporter in a slavshit cheapo caliber I'm working towards.

that doesn't really teach you design

>learning design before learning what's necessary to create and the limitations of said design
IWI is hiring.

Don't know how much "gunsmithing" this is, it was built from an 80 lower though.

Not a huge handgun guy but just finished this build. Go ahead and roast me.

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wheres the flutes

disregardMisread post

If you expect to get all the info you need from one place in a tidy package you're gonna have a bad time

missing the point. knowing how to make a part is a completely different skillset from knowing how to design one. if you want to design guns you have to be a savant like browning or study engineering.

The name of the game is "Design For Manufacturability".

The best drafters are machinists and the best engineers are drafters.

Bingo bongo.

and you still need to be an engineer. I can make a bolt head if you give me a blueprint for it. I don't even have the slightest idea what angle the camming surfaces should be without a blueprint.

It's a lot easier to do drafting or machining as a starting point and then moving on from there.

t. not an engineer

Quality machinists and drafters are invaluable and have a wealth of knowledge which any good engineer will leverage, but they are not engineers and generally are not capable of becoming one.

>and generally are not capable of becoming one
In my experience, at least, that's complete and utter bunk. The overlap is often extensive.

If you don't understand what that saying means, you need to reflect on why drafters and machinists make fun of you.

Lotta uppity drafters and machinists in this thread thinking it's easier to learn engineering than it is to learn their basic shit.

Just had a magazine catch made for my Mauser project. Needs some hand fitting but I'm one step closer to completion.

Attached: mag catch 2.jpg (1920x1080, 565K)

That's the exact opposite of what I said, though.
You're like the textbook example of an autistic engineer(ing student).

>The overlap is often extensive
It depends on the industry, though certainly can be the case. Little to no overlap in aerospace composites where I have spent most of my career. The same is true for most "higher end" fields.

Oh, for sure if you're talking aerospace or other comparable fields.
Gunsmithing though, or other "crude" fields, not so much.

Nice try Cletus. I do mechanical engineering, DFM, and technical drawing professionally, and the latter two are by far the easiest to pick up.

user, are you trying to be a retard?
What I said:
>It's a lot easier to do drafting or machining as a starting point and then moving on from there.
If it's EASIER to do drafting or machining AS A STARTING POINT, when the concept of being a well-rounded engineer is that you have a base in both machining and drafting, then does that mean that engineering is EASIER or HARDER than the things that are EASIER TO START WITH?

Want to know why machinists and drafters often make fun of engineers? Because the engineers who get made fun of act like snooty retards. If you were just a retard or just snooty, they may not like dealing with you but they wouldn't actively make fun of you. The combination of both where you think you're smarter than everyone else because they have a different specialization, even if only for now, is what makes you so fucking comical.

Just keep digging that hole deeper, draft monkey.

Answer the question.

You know he's not actually an engineer, right?

IDK, man. I've met some pretty stupid people of all stripes, engineers included.

Saw one guy who wanted to design a brand new screw that EXACTLY met strength requirements... instead of just using the next standard size up.

Oh good lord don't get me started on the fastener autists.

Or how about making perfectly rectangular pockets.
Does it NEED to be rectangular?
>YES, BECAUSE I SAID SO
... Because to make it we'll have to--
>JUST DO IT
It turns out, milling a pocket with a radius in the corners or some simple relief cuts on a mill is cheaper to do than EDM. WHO KNEW?
Apparently not that engineer.

>perfectly rectangular
It hurts. Like dude do you understand what that requires because I don't think you've thought about it.

Hey, if he doesn't value my input, then he can get yelled at by management. Team work is a two-way street.

If a welder shows up at my desk and says "hey, this assembly could cause problems/could be done better here...", I fucking take the time to hear him out, we quickly sketch it out and we end up with a better fucking product. It's not fucking hard.

I feel like we've had this same exact conversation a few times now.

Possibly. There are only a handful of people on Jow Forums with the knowledge base to really participate in these threads outside of asking questions.

You should see some of the retarded designs the machinists send to me to try to simplify things for production. I've had to revise someone's work three times because they keep trying to get something okayed that will not work.

Hi, I'm starting at Boeing as a machinist with no machining experience. How do I not fuck up?

keep your eyes and ears open. no one is ever past the point where they need to keep learning things.

Be very open to learning. Thank you kind user!

Nothing at the moment but I did install a paddle magazine release in my PTR C93 last week.

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>why do they make fun of engineers?
Precisely that very reason

This conversation plays out across all relevant platforms every day for as long as the language has existed to do so.

At the end of the day a firearm is a really simple engineering challenge, with a lot of the work having been done by others and a lot of that information available free of charge online. A thorough understanding of machining is not so easy to come across. Knowing what's possible and feasible to fabricate is the part that can't be outsourced if you're doing a scratch build as a creative venture.

1) Is there such a thing as standard inner diameters for chambers, or a way to calculate what their inner diameter should be? For example, the case's diameter for .357mag is .379, so I guess the chamber should be just a little tad bigger. How much? .380? .385?

2) I've heard chamber wall thickness "should" be around 2/3 the diameter of the case. This is not very scientific, but it usually works. How come revolvers have such thin chamber walls, then? Many are less than 1/3 the diameter of the round. Are the chambers of a revolver's cylinder weaker than that of a normal firearm?

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need more educated opinion on this or direction/sources to search.
general question is: what is an acceptable head clearance margin for .223/5.56? not talking about ARs, but something like an AK in .223 or similar

picrelated is the specific issue I'm trying to research. the second shot is an extreme closeup, this might create a skewed perspective of the clearance, just keep in mind the ratios. the last shot is of a 5.56 round, with the arrow pointing to the scratch noting the threshold where the case has full support.

those who know what I'm talking about, please take a look and give me your thoughts on how normal or abnormal this head clearance is for 5.56

Attached: case support.jpg (1446x2566, 895K)

1) look up the saami chamber drawings for the cartridge
2) look up hoop stress

Thanks.

I've known people who won't talk to you unless you have an associates degree in something, lol

>1)
saami.org/technical-information/cartridge-chamber-drawings/
>2)
This is complicated, because there's two reasons you need wall thickness.
One is so the chamber doesn't burst, obviously -- so using the cartridge pressure, the yield strength of your material, and a factory of safety, you can figure out what it needs to be. Look up "thick wall pressure vessels" for the formulas you will need. Point is, for any given cartridge and wall thickness, there's some strength of material that will make it work -- and while at some point you run out of stronger materials, you can generally go well below a wall thickness of 2/3 the case diameter.
Also, this generally goes by the thinnest point -- if one spot (such as the outside edge of a revolver cylinder) is too thin for the stress it's carrying, the cylinder is at risk of bulging or rupturing. "Weak link" and all.
(1/2)

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The other is ease of extraction. Any chamber will momentarily stretch in diameter at the moment of firing, then relax to its previous size. If you use a very thin wall around the chamber (with very high strength steel to keep it from bursting), it will stretch more than if you use a thicker wall; since the cartridge case expands to fit the stretched chamber, it will now be tightly locked into the relaxed cylinder. This is why .357s on .38 frames, and thus with thin cylinder walls, experience difficult ejection with full-power loads, while ones built on .44 frames, with the resulting thicker, less stretchy, cylinder walls, can handle those loads and eject them easily.
For something like a revolver cylinder, the overall rigidity matters more than the weakest spot -- if the outermost portion stretches a little more from being so thin, but the rest stays pretty rigid (due to the wall thickness and honeycomb support from adjacent chambers), you may be just fine -- the cylinder will go kind of oval-shaped at the moment of firing, and the brass will be correspondingly oval, but it'll still be on average smaller than the relaxed cylinder. So it'll have contact at two points, and exhibit noticeable drag, but it won't be locked up solid where you have to drive the cartridges out.
This effect is also related to pressure, but unlike bursting is based on the modulus of elasticity. Since all steel has essentially the same modulus, there's nothing to do about it but use thicker walls -- this is where the 2/3 rule comes from (it applies to rifle cartridges with ~60ksi, BTW).
(If you're contemplating materials other than steel, then you can vary your modulus of elasticity, but mostly in the wrong direction. Titanium, copper, brass, and their alloys generally have about half of steel's modulus, and Aluminum about a third. Tungsten or silicon carbide have double steel's modulus, but are not really suitable.)
See yarchive.net/gun/ammo/cartridge_expansion.html
(2/2)

Hello fellow c96 builder. How’s the part hunting going? I’m still trying to find a 1930s lock frame for my 1930 build but I do have all my other parts except a receiver for my 1920s bolo

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I've considered fabricating my own little sporter .22 using a kropatchek style magazine system. The lifter is insanely easy to mill and the system is mechanically very simple. I could steal the magazine from a Henry and the barreled reciever and action from a beater .22. I'd have to do some handfitting, as well as modifying the reciever to fit the lifter, but I think it would be really cool.

Looks beautiful, bud. I'd be proud of that.