jim in Anchorage
Member
- Joined
- Feb 28, 2009
- Messages
- 2,849
tark
Do those guns have to be serial numbered and somehow registered with the gov?
Do those guns have to be serial numbered and somehow registered with the gov?
Making a gun from scratch
- Thread starter tark
- Start date
- Status
OP
OP
tark
Member
Hi, Jim. Certain conditions must be met before you can make your own firearm.
You must be legally entitled to own a firearm in the first place. You cannot make an NFA firearm. The gun you make must be for your own use. You can't make a gun for someone else without an FFL. I'm pretty sure they can be passed on to your kids. Not sure if serial #s are a requirement or not, but mine are all serial numbered. (1) I'm not really sure if there is a limit on how many guns you can make. Someone with more knowledge of the law may weigh in.
There is no requirement to register them with anyone, as far as I know, at least at the federal level.
Tark and Jim, here is a good video going over a bunch of laws regarding home builds by another member of this forum that should clear up some of your questions. Listening to the whole thing will be beneficial to any gun owner but if you know about NFA rules his non-NFA discussion about home builds starts going at around the 11 minute mark.
OP
OP
tark
Member
Excellent info bullzeye8 ! Thanks for posting it, it clarified a couple of points I wasn't sure of. So I CAN sell one of my guns (not that I want to) if I didn't make it with the intent of selling it. And I thought you were required to put a serial# on the gun but it isn't required.
I'm hoping some of the guys making their own from scratch guns will weigh in here. I seem to remember a 1/2 scale AR that someone was building that was incredible! What I saw was the work of a Master Machinist, far above the skills required to make simple single shot guns like mine.
I'm hoping some of the guys making their own from scratch guns will weigh in here. I seem to remember a 1/2 scale AR that someone was building that was incredible! What I saw was the work of a Master Machinist, far above the skills required to make simple single shot guns like mine.
lysanderxiii
Member
Bold is incomplete. You must have a type 07 Federal Firearms License (manufacturer's license). Your run-of-the-mill dealer/gunsmith Type 01 FFL is insufficient for manufacturing. (That actually includes assembling from parts with the intent to sell.)
Last edited:
OP
OP
tark
Member
Quite right, I just couldn't remember what type of FFL was the manufacturer's licence so I just said "FFL." I was partially correct, I guess.
MachIVshooter
Member
Guess not everyone has made the connection yet
That's my channel, and that video was done to help clear up so much of the confusion and myth surrounding home building. State laws vary a bit, but most don't really address it at all. Obviously, if your state has registration, though, home builds are not exempt.Single shot or not, your builds look great! One thing I'm not as good about with mine is having the patience to sit there and hand finish for months or years to get some of the classy lines and contours. Most of my builds are completed in 1-2 months with 120-160 hours invested, and they tend to be rather angular/geometric in form. I also don't build existing designs, save for the GB-380, since Mark sent me the plans and asked me to do a "nice" machinist's version of the GB-22 design. I haven't done a build since January, though. Been busy with other things. Another featherweight pack rifle is slated to begin soon, this time a .22 mag with a Ti receiver. Also a .45 Colt semi-auto rifle and a 10mm version of the Hammerli 280 on the to-do list, but they're still just rough images in my head right now. I haven't even decided what I want to do for operating system on the .45 Colt, although I'm seriously considering an adjustable gas system that would allow for use of .454 Casull.
I still haven't got the AR-7.5 running right, haven't really tinkered with it in awhile. It's a problem with bolt weight, and that some things don't scale well. I've fired it many times, but it's a single shot that sometimes blows case heads, in spite of going to a pure tungsten buffer and a nearly solid bolt made of 8620 steel. .17 HM2 is just an energetic little round.
I'd direct you guys to some of my threads, but as I used Photobucket to host all of my images, their recent cash grab has left those threads devoid of images. I will not pay $400/yr to host photos.
OP
OP
tark
Member
The three pistols have no heat treated parts. The breech blocks and hammers on them are 1045. When you go this route, you must make the contact surfaces on the load bearing parts quite large, to absorb the stress of firing. I made my own head space gauges for all three. None of them has stretched or increased head space at all. One advantage in using relatively soft steel is that it will stretch and bend, rather than crack or shatter, most of the time. This is a general, not an absolute, rule. I don't shoot the pistols a lot, although the 45 PITA has had several hundred rounds through it. Most of them were black powder, which isn't exactly high pressure ammo. It does like a 385 grain 45-70 bullet ahead of a case full of RX-7, which comes out at about 18 grains. It has very little recoil or noise and I doubt that it is getting more that 600 or 700 FPS. Sure does ring a gong, though!
MachIVshooter
Member
That's more of a one-time overload rule. Nearly all metals will stretch and/or work harden, which embrittles and weakens the material, results in tearing or stress cracking. The simple way to think of it is bending a piece of mild steel. Yes, it will deform, where a really hard alloy would snap (at a much higher load, mind you). You can bend it back, but it will be weaker at the stress point. Keep doing it, eventually it will snap. This is the result of exceeding the yield strength of the material; the point at which it deforms permanently.
When examining the mechanical properties of alloys, many folks' first (and perhaps only) inclination is to compare UTS. That is, ultimate tensile strength. It's an important figure, but the yield strength is moreso, since, again, that is the point at which the material will permanently deform. Mild steels tend to have a much lower yield strength relative to their UTS as compared to treated medium or high carbon steels. Let's take a look at A36 low carbon steel, about the most common consumer material. It has a UTS of 60-80 KSI, but the yield strength is only 36 KSI. That means that if you have .25 sq. in. bearing surface (remember, that'd be 1/2" x 1/2", not 1/4" x 1/4"), 9K lbs of bolt thrust will permanently deform it, even though it shouldn't shear on the first shot. Virtually all common medium bore bottle neck cartridges exceed that force, the .308 win running about 11K lbs. Meanwhile, 4140 steel with a 1,000°F temper has a yield strength of 140 KSI, about 4 times as much, which could handle even the 28K lbs of thrust generated by the .50 BMG on that same .25 sq in bearing surface. Your 1045 alloy in the cold drawn state has about twice the strength of A36. Quenched & tempered, it actually exceeds 4140 by a fair amount.
That's one of the reasons I like 6/4 Ti; in the annealed state, it has nearly the same yield strength as tempered 4140. Not easy to work with, though, and does have some drawbacks.
7075-T651 aluminum is another go-to material for me, but it doesn't have the fatigue strength or fracture toughness of steels with similar yield strength (70 KSI), so it's applications are more limited.
Metallurgy is a very complex subject, and I'm by no means an expert. But I do know enough to tell people that they need to carefully research the materials they are considering using for any project, and especially one that is containing explosive force right next to or in front of your face. There's more than one way to skin a cat, so to speak, and you can certainly over-build on account of questionable or unknown materials, but some should just be avoided entirely. Black pipe for shotgun barrels, for example, is just plain dangerous, as is using brake line for .22 rimfire.
The information is out there, and the math isn't that difficult. Yes, many materials require heat treatment/tempering to achieve optimal mechanical properties, but some are available pre-treated, and often actually machine easier that way. 4140HT is much less stringy and sticky than normalized or annealed 4140. If you want to take on heat treating yourself, remember that some materials are more forgiving than others. Sometimes you can get away with torches/forges using the color method, others really need a high accuracy oven and a good, long soak.
For any of you who are interested in taking up this hobby, I would say forget about hardware store or box store steel. It's pretty much all A36, maybe some 1018 CR, and it's ridiculously overpriced. In the small quantities you'll need, shop online. eBay is a good source for best price, but onlinemetals.com and a number of others are probably your best bet if you need specific alloys in specific sizes. Everything you could want is literally at your fingertips, including exotics like various Ti grades, martensitic stainless, Inconel, and so on. And the same rule applies to fasteners; won't do you any good to use tempered chromoly steels for breech parts if a crappy gr. 3 zinc plated bolt is all that's holding it together. I recommend hardened pins or spring tempered music wire in properly reamed holes and, once again, make sure the shear strength of the material at a given size is up to the task!
ETA:
Here is a good source for bolt thrust of various cartridges:
http://www.orions-hammer.com/blowback/
And this is a great one for researching material properties:
http://www.matweb.com/
lysanderxiii
Member
With 1045, I would strongly suggest case hardening it.
With Kasenit and good hot fire, you can at least put a hard surface on it, which goes a long way.
(And, you get those pretty colors.)
lysanderxiii
Member
Something that most people don't know or don't fully understand is that that the assembly of parts is also considered "manufacturing" in the eye of the ATF.
So, if your buddy comes over to your house with a box of AR parts, and while he is out buying the beer, you decide to get a jump on things and go ahead and put all the parts in the lower, technically, you have just broken the law . . .
lysanderxiii
Member
For those truly interested in gun design, I strongly suggest reading "The Machine Gun" by Lt Col George Chinn, USMCR
The whole set is a good reference, but Volume IV has a very good section on design. It will allow you to get things right the first time, if you do the math.
Ask you local library if they can get a copy through other (usually university) libraries.
OP
OP
tark
Member
PITA stands for "pain in the you know what" I called it that because cutting the 45-70 cases down to 1 1/4" is exactly that. I also had to modify a set of 45-70 reloading dies in order to reload for it.
MachIVshooter, thank you for the excellent info! I will learn a lot today, I would think. By actual measurement, the load bearing surface on the 45PITA, where the breech block pushes against the hammer, is 5/8" X 3/8". The pins are 1/2 inch in diameter, and each sidewall on the receiver is 3/8" thick. Pins themselves are drill bit shanks, so I know THEY are hard I have made a headspace gauge, of sorts, to test for spring or deformation of any parts. When I chamber the gauge and close the breech block and carefully lower the hammer, it will come within 3/8" of touching the firing pin. If it ever comes any closer, or reaches the firing pin I will know something is wrong. Something has yielded to stress. So far so good.
LysanderXIII Again, thank you for some good advice and information. I will get Col. Chinn's books, they sounds like good reading. Sounds like there is more than one. I have seen good reviews in several gun mags.
MachIVshooter
Member
Oh, I didn't mean to imply that your bearing surfaces were insufficient. That was more a general statement to all who are considering this hobby to be mindful of the mechanical properties of the materials being used, and design accordingly (with a decent safety margin).
As for HSS twist drills as pins, they'll do the duty, but remember that they are through hardened with a hard temper (Rc 60+), which is great for a cutting tool, and they have high shear strength, but they are also brittle, so don't deal with shock loading well, which will be present if there is any play in your arrangement. That's why I suggest spring temper music wire, which has medium hardness (~45 Rc) with very high toughness. Or case hardened pins, which are very hard on the outside, but have a much softer core, so won't snap like a through hardened pin.
That's also one of the advantages to steels like 8620, which takes a double heat treat. The yield strength is actually lower than 4140, 1045 and a lot of other heat treated medium and high carbon steels, but that initial through hardening followed by case hardening gives you a very tough part with a very hard case. This is the alloy used for AR barrel extensions, M60 machine gun bolts and many other critical firearm parts. I used 8620 for the bolt in my 9mm pack rifle.
There's always a balance in wear resistance (hardness) and toughness with gun parts. One way to get around having to heat treat is to use existing tools. Generally somewhat difficult to work with, but that tricky heat treatment is already done. Some of the internal parts on my builds are cut from production chisels and punches, which are treated to medium-high hardness and high toughness, so they resist wear and take impacts well.
OP
OP
tark
Member
I am learning a lot from your posts! Thank you so much!!
I am a rank amateur when it comes to metallurgy, which means I probably shouldn't be making guns with non-heat treated metals in the first place. But my pistols have never had more than the very mildest of loads run through them. I knew that with the centerfire rifles I would have to have the parts heat treated as the stresses would be enormous. That 45-70 was proved with a 500 grain JSP seated in the leade with enough room behind it for a 65 grain charge of RX-7. I used a Remington 45-70 case. They have the thickest brass. The bullet was actually seated ahead of the case, in the same position as it would be in with a 458 round. The gun ate it with no problem.lysanderxiii
Member
Actually, M60 bolts are made from 9310.
As to the rolling block design, remember the original design was just plain carbon steel with a relatively thin case hardening, and the Ariska and WW2 German Mauser were made from 1085 (equivalent).
mountian girl
Member
- Joined
- Jan 13, 2017
- Messages
- 42
i want one,,,,,,,,,,,,,,,,,,,,,,,,
- Status
