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80% Arms:80% Lowers

The above make REALLY nice looking weapons. They offer them finished or in the white, even blems. When I'm building a weapon for me these are the ones I use. They have uppers as well, with or without FA. Other than that stay with a forged. I have bought forged ones in the white from many places and they ALL look the same. You will pay more for the Billet, but they are worth it to me in the way the finished result turns out.
They are nice. I just did one for a pistol a couple weeks ago.
I think a lot of the common forgings come from Cerro.
 
No one has brought this up yet so I will. 80% builds are addictive. You build one and a year later it's got 3 siblings. But it gets worse, you start your friends down the same path. The guilt is crippling.
 
FWIW - a builder needs to think about the purpose of the firearm and the accoutrements you will be attaching.

One of the three that I will build will be a 'get home' pistol in 7.62x39. This will have a 10 to 14" barrel, and preferably lighter weight components. One of the things I wish to add to it is a DigiTrigger, which requires a removable trigger guard to be installed. I have noted that most of the billet lowers do not have a removable trigger guard.

Also, there is something to be said for the strength of a forged part vs. billet, and especially forged vs. cast.
 
I think there is little if any gain between the cast, forged, and bullet as to strength and durability, if you think about it, it' the upper thayvsees all the stresses, and even there the barrel is fully supported and takes all the firing stresses, so tecinally it shouldnt/dissent matter which way you go othe then overall quality of the material used! Outside Mil requirements of cycle rates and corrosion resistence, there is no real gain between parts! So, unless your just into billit, or money spent equals cool, don't bother!
 
I think there is little if any gain between the cast, forged, and bullet as to strength and durability, if you think about it, it' the upper thayvsees all the stresses, and even there the barrel is fully supported and takes all the firing stresses, so tecinally it shouldnt/dissent matter which way you go othe then overall quality of the material used! Outside Mil requirements of cycle rates and corrosion resistence, there is no real gain between parts! So, unless your just into billit, or money spent equals cool, don't bother!

I am sure 95% of you know this but a forged lower starts out as a billet that is almost exactly the volume of aluminum required and using heat and force the volume is moved to where it is needed using multiple stage dies and a press that is hundreds (if not thousands) of tons. The forging process refines the grain structure and pushes it to follow the shape of the part resulting in the strongest possible cross section for a given volume.

A billet starts out as a much larger chunk of aluminum than the volume required and through the removal of material during the machining process everything that is not "receiver" is machined away. I suspect it takes a third more aluminum to make a receiver from billet as it does through forging. It is also not as strong for a given volume as the grain does not follow the form of the receiver but rather is all in a single plane and in places can cause stress focal points just as the grain in wood.

A cast unit is molten aluminum poured into a cavity in the shape of a receiver. This is the weakest as there is no refinement of grain in a casting. The molecules of material are jumbled up resulting in weaker bonds to its neighboring molecule. There is also the possibility of inclusions (air, debris or any other impurity) that become trapped as the molten material solidifies. It also shrinks as it cools which results in poor surface characteristics and a less than a precision product. It is however the cheapest and easiest way to produce an aluminum part. Most all castings will be 6000 series alloys as 7000 series (which is much stronger) are not a castable.

So... By a given weight of a given alloy, a forging will be the strongest. This is why billet receivers tend to be a bit bulkier. They are engineered to replace the strength lost due to the nature of machining into the grain structure of the material. The appeal of billet receivers is they allow for small runs (comparatively, it would take tens of thousands of parts to offset the cost of a single set of dies using in forging which could run several hundred thousand dollars) and allow for design and detail that is beyond what is possible with a forging.

So long story short... Both 7075 forged and billet receivers are comparable in strength but a forged one will tend to be lighter. A cast one is an inferior process most likely using an inferior alloy and the only reason they are produced at all is low cost.
 
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I am sure 95% of you know this but a forged lower starts out as a billet that is almost exactly the volume of aluminum required and using heat and force the volume is moved to where it is needed using multiple stages dies and a press that is hundreds (if not thousands) of tons. The forging process refines the grain structure and pushes it to follow the shape of the part resulting in the strongest possible cross section for a given volume.

A billet starts out as a much larger chunk of aluminum than the volume required and through the removal of material during the machining process everything that is not "receiver" is machined away. I suspect it takes a third more aluminum to make a receiver from billet as it does through forging. It is also not as strong for a given volume as the grain does not follow the form of the receiver but rather is all in a single plane and in places can cause stress focal points just as the grain in wood.

A cast unit is molten aluminum poured into a cavity in the shape of a receiver. This is the weakest as there is no refinement of grain in a casting. The molecules of material are jumbled up resulting in weaker bonds to its neighboring molecule. There is also the possibility of inclusions (air, debris or any other impurity) that become trapped as the molten material solidifies. It also shrinks as it cools which results in poor surface characteristics and a less than a precision product. It is however the cheapest and easiest way to produce an aluminum part. Most all castings will be 6000 series alloys as 7000 series (which is much stronger) are not a castable.

So... By a given weight of a given alloy, a forging will be the strongest. This is why billet receivers tend to be a bit bulkier. They are engineered to replace the strength lost due to the nature of machining into the grain structure of the material. The appeal of billet receivers is they allow for small runs (comparatively, it would take tens of thousands of parts to offset the cost of a single set of dies using in forging which could run several hundred thousand dollars) and allow for design and detail that is beyond what is possible with a forging.

So long story short... Both 7075 forged and billet receivers are comparable in strength but a forged one will tend to be lighter. A cast one is an inferior process most likely using an inferior alloy and the only reason they are produced at all is low cost.

So with the forging process effectively increasing the density of the metal, does that mean a forged lower will be tougher to process? Harder on bits?
 
If you are noticing a difference in machining it's probably that one is a 6061 alloy and the other is a 7075. The forging should not make a difference on how it machines.
 
I haven't taken the time to research this and I am pretty sure that I know the answer but here it goes.

If you do put a serial number on a 80% lower is it legal to sell? For instance if I did that could I give it or sell it to my SIL?
 
I haven't taken the time to research this and I am pretty sure that I know the answer but here it goes.

If you do put a serial number on a 80% lower is it legal to sell? For instance if I did that could I give it or sell it to my SIL?
According to my FFL you can transfer if you apply a serial number and do the BGC
 
Not being a machinist, can you help me with the type of reamer you're referring to. When I think of a reamer, I think of a pipe/conduit reamer, which I'm sure is much different than what you're talking about.
yep just use a portaband, pony reamer and a tri-stand for it, boss. u got this






:p:D:D:D:D:D:D:D:p:cool::rolleyes:
 
I haven't taken the time to research this and I am pretty sure that I know the answer but here it goes.

If you do put a serial number on a 80% lower is it legal to sell? For instance if I did that could I give it or sell it to my SIL?

just have him "borrow your jig and machine it himself"





just sayin
 
As far as adding a serial number and doing a transfer goes, it's my understanding that what MilitantBEEMER said is correct. However, that kind of defeats the purpose of an 80. A stripped lower that was fully machined and manufactured with serial number already costs less to begin with. If i were to sell an AR that was built on an 80% lower I'd likely just break it down and sell it as a rifle kit, keeping my 80. The buyer can add their own lower and keep me out of the system. Just my .02.

To v0lcom's point about the jigs, I'm the same way. I'd rather own my tools and decide whether or not to share. In the case of the 80%EZjig, some of the parts are somewhat consumable and I explain that to anyone I might loan to. The replacement pieces aren't really expensive but do cost money so I let borrowers know that. Gratuities aren't required but are appreciated. I also don't share bits. If someone wants to borrow my jig they can buy their own.

There is a premium for rolling your own. In the current market it makes absolutely no financial sense to do this. If Washington and Oregon were still free states and weren't taxed the additional $25-$75 to transfer it would make even less sense. I would say that between the cost of the jig, replacement parts, and bits, there is around $50 in machining each lower if you already have all the other tools and your time is worth nothing. That being said, at least it's still legal (for now) and it's a somewhat satisfying experience. Just don't try to justify it as a cost saving endeavor.
 
I agree, Doing a good job on a 80% lower will cost you some real time and cost at least several times what a cheap lower can be had for. I have had rifles built on 80% lowers that I decided to sell. I bought a cheap Anderson lower and swapped all the parts to it and kept my 80% lower even if I didn't need it. I bought a whole pile of Anderson lowers for $29 each. At that point there is no reason to give up one you spent hours machining and finishing.
 
I haven't taken the time to research this and I am pretty sure that I know the answer but here it goes.

If you do put a serial number on a 80% lower is it legal to sell? For instance if I did that could I give it or sell it to my SIL?

I was told NO by the local ATF during my licensing interview. I was told that by doing so you are considered a manufacturer with out a proper license. Take it for what it's worth, but I personally don't want my cats stomped or ninjas busting down my door at 02:00 some night.
@IronMonster said it best. 80%ing isn't to save money-esp with current prices, it's for the joy/love of making something with your own two hands or to have no paper on. For me it's a bit of both.


i really need to buy a jig and router! a buddy wants to "go in on a jig" with me but something about me using tools to make my living doesnt like that. my tools are MY tools. u know?

I do know.
I have "sponsored" a few build parties and this may be the best way to go. I am there to watch over and guide folks, they use my stuff and build their own-no laws broken and it's GREAT FUN with the right bunch of guys..
 

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