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perfectscore
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Posted: 12/5/2008 9:37:30 AM EST
What are the advantages/disadvantages of uppers and/or lowers machined from billet or forged aluminum?
sporter
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Posted: 12/5/2008 9:44:11 AM EST
[Last Edit: 12/6/2008 8:06:52 AM EST by sporter]
Forged is typically a piece of material that is smashed into a shape while it is red hot (when referring to a shaped object for rough or final product).
The grain structure of the metal material will follow the shape of the unit being produced.
(ETA: forged material can also have no particular shape to make forged blank material to be machined into smaller pieces but retaining the strength of the initial forge)

Billet is a more general term used to describe a piece machined from a chunk of material/metal.
The original piece is most likely some sort of casting or drawn out, formed piece of metal.

In simple terms forged is probably going to be stronger.
Billet strength is dependent on the original slug of metal it was machined from.

Billet uppers or lowers can be more pleasing to the eye however due to more machining operations to achieve the final product. A forged or cast piece will usually be a rough resemblance of the final product and some areas may not need a finished surfaced machining/milling.

To add to the confusion you can have a piece that is forged and billet at the same time if the parent material stock was forged.

On another note: Take for instance a crank shaft for an engine that is forged into it's final shape then machined.
The shaped forged crankshaft would be stronger than a crank that was machined from a forged piece of billet material due to the grain structure following the shape of the forging.
theanimal_650
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Posted: 12/5/2008 9:48:55 AM EST
Actually forging is the process of smashing the metal to compress the molecules in the steel therefore making the steel much stronger. Sometimes it is forged into shape but that is not necessarily always the case. Most of the time the finished part will be machined from a block or round bar just as it would be from a billet.
the only difference would be that the part machined from the forging would be stronger than the standard billet. Of course this is assuming we are talking about the same parent material.
djm227
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Posted: 12/5/2008 10:20:24 AM EST
Are they any functional advantages of getting billet over forged? They're so much more expensive, but are they at all better?
zombie92272
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Posted: 12/5/2008 10:25:06 AM EST
I have Both.....''SAME SHIT'' ...Billet Looks Cooler
SamColt
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Posted: 12/5/2008 10:30:38 AM EST
Originally Posted By djm227:
Are they any functional advantages of getting billet over forged? They're so much more expensive, but are they at all better?


no. buying "billet" is the act of spending more for less.
VLTOR's billet MUR is now a forged MUR and the best upper on the market IMHO. The .mil requires forgings for a reason.
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Hanover_Fists
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Posted: 12/5/2008 11:27:59 AM EST
[Last Edit: 12/5/2008 11:28:59 AM EST by Hanover_Fists]
Originally Posted By djm227:
Are they any functional advantages of getting billet over forged? They're so much more expensive, but are they at all better?


The advantages are in the manufacturing; a forging requires a large initial investment in tooling, but the payback comes in the ability to mass produce consistent, strong parts relatively cheaply on a per item basis.

Manufacturing from a billet (assuming a forged billet) has a lower initial cost investment for the manufacturer since the parts are produced on a one-off basis. The drawback of this approach is that it takes longer to produce a part, and is therefore more expensive on a per item basis.

The strength issues compared to a forged part can be compensated by adding more material in the billet part, but realistically I don't believe that the strength differences between a forged billet upper/lower and a forged upper/lower are all that great.

nicholsmf
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Posted: 12/5/2008 12:23:20 PM EST
[Last Edit: 12/5/2008 12:23:59 PM EST by nicholsmf]
In before Wes from MSTN

ETA: Billet is "prettier" that is all
2012
skipsan
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Posted: 12/5/2008 2:28:09 PM EST
My machine shop fabricated (machined) structural steel parts for a large manufactuer of commercial airplanes. The parts were of moderate size with the finished-machined parts weighing 10 lbs or less usually. Our customer (the airplane maker) provided forgings for those parts, but in every case there was a "bar-stock" option on the part drawing in case the forgings were not available. The barstock was "forged" from ingots of the same material as the more-net-shape forgings. The only advantage offered by the forgings was that less material had to be removed to get to the finished part and were therefore cheaper. The parts were structurally equivalent whether they were machined from forgings which looked, generally like the finished part, or from forged bar which looked generally like "bricks" of 4340M high strength steel.
BattleRife
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Posted: 12/5/2008 2:42:14 PM EST
Originally Posted By sporter:
Billet is a more general term used to describe a piece machined from a chunk of material/metal.
The original piece is most likely some sort of casting or drawn out, formed piece of metal.

No, the original piece is a billet. A billet is an intermediate wrought product between a bloom and finished stock.


Originally Posted By theanimal_650:
Actually forging is the process of smashing the metal to compress the molecules in the steel therefore making the steel much stronger.

Interesting. Please explain to me the mechanism of molecular compression. Assuming, of course, that steel had any, which it doesn't.



Originally Posted By djm227:
Are they any functional advantages of getting billet over forged? They're so much more expensive, but are they at all better?

No.
P7-PSP
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Posted: 12/5/2008 4:17:02 PM EST
A billet lower receiver is often finished up into a much more attractive, unique end product than is commonly found in straight forged receivers.

Look at a Sun Devil, Tactical Innovations, or POF billet receivers. Very, very nice looking units. Personally I prefer having at least one or more of my AR's built up on a billet receiver.

I think that because of the ability to add intricate strengthening areas to a billet receiver also makes for a superior product......but I am not a structural engineer.
P7-PSP
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Posted: 12/5/2008 8:42:04 PM EST
I forgot to mention the excellen billet lower receivers made by SMOS, that LaRue uses for their Stealth receiver system. A work of art like most billet lowers.
vicious_cb
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Posted: 12/5/2008 8:47:46 PM EST
In short billet receivers cost more, look pretty and dont do anything better regular stuff. In short its like jewelry.
vicious_cb
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Posted: 12/5/2008 8:48:44 PM EST
Originally Posted By P7-PSP:
I forgot to mention the excellen billet lower receivers made by SMOS, that LaRue uses for their Stealth receiver system. A work of art like most billet lowers.


Too bad SMOS screwed the pooch by signing up with larue. They would have made a killing with the obama craze

theanimal_650
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Posted: 12/6/2008 1:52:20 AM EST
Interesting. Please explain to me the mechanism of molecular compression. Assuming, of course, that steel had any, which it doesn't.


Always a scientist in the bunch

I was just trying to let the guy know that forging is smashed for strength and doesnt necessarily need to be smashed into any particular shape. Very sorry if my wording was wrong
SBCZILLA
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Posted: 12/6/2008 3:01:46 AM EST
Especially on a lower. Spending money on something that does exactly DICK!


For some reason, people have yet to figure out that the lower does nothing but house the trigger assy, contain 2 takedown pins that have ZERO stress on them, and hold a stock. Thats it.


Its like having an even tougher, pimped out, polished sledge hammer.

better, but why?



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jws360
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Posted: 12/6/2008 7:32:28 AM EST
Originally Posted By SBCZILLA:
Especially on a lower. Spending money on something that does exactly DICK!


For some reason, people have yet to figure out that the lower does nothing but house the trigger assy, contain 2 takedown pins that have ZERO stress on them, and hold a stock. Thats it.


Its like having an even tougher, pimped out, polished sledge hammer.

better, but why?



Would you say the same with respect to comparing cast and forged lowers?

Why or why not?

sporter
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Posted: 12/6/2008 8:02:45 AM EST
[Last Edit: 12/6/2008 8:05:00 AM EST by sporter]
Originally Posted By BattleRife:
Originally Posted By sporter:
Billet is a more general term used to describe a piece machined from a chunk of material/metal.
The original piece is most likely some sort of casting or drawn out, formed piece of metal.

No, the original piece is a billet. A billet is an intermediate wrought product between a bloom and finished stock.


Originally Posted By theanimal_650:
Actually forging is the process of smashing the metal to compress the molecules in the steel therefore making the steel much stronger.

Interesting. Please explain to me the mechanism of molecular compression. Assuming, of course, that steel had any, which it doesn't.



Originally Posted By djm227:
Are they any functional advantages of getting billet over forged? They're so much more expensive, but are they at all better?

No.


I guess I should have been more clear.
I know the definition of billet. But for this conversation the OP is referring to a billet upper or lower.
The seller of billet lowers, uppers, receivers often refers to them as "billet lowers" for marketing purposes. Same as many manufacturers refer to forged pieces as "forged steel" "forged aluminum" etc. etc.

Instead of picking apart everyone's posts maybe you can write up a little piece on billet vs. forged.

SBCZILLA
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Posted: 12/6/2008 12:46:27 PM EST
Originally Posted By jws360:
Originally Posted By SBCZILLA:
Especially on a lower. Spending money on something that does exactly DICK!


For some reason, people have yet to figure out that the lower does nothing but house the trigger assy, contain 2 takedown pins that have ZERO stress on them, and hold a stock. Thats it.


Its like having an even tougher, pimped out, polished sledge hammer.

better, but why?



Would you say the same with respect to comparing cast and forged lowers?

Why or why not?




Not at all.

A forged lower is something you want, but a billet milled one is overkill.
Cast is weaker, and more brittle. And is just like the name says. Its "cast" into a mold.

Think pot metal on your gun. Avoid.

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BattleRife
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Posted: 12/6/2008 2:12:28 PM EST
Originally Posted By theanimal_650:
I was just trying to let the guy know that forging is smashed for strength and doesnt necessarily need to be smashed into any particular shape. Very sorry if my wording was wrong


Which is why I went all scientist on you. Billets are the product that is forged in no particular direction (open die or rolling mill). The parts that you usually see described as "forged" are actually closed-die forgings, meaning that the stock is forged to a near-net shape and avoiding re-entrant flow lines, which means that the directionality of the grains flow with the shape of the part, which in turn minimizes anisotropy in the component.

So a part described as "forged" in AR-15land is indeed usually smashed into a particular shape.

Originally Posted By sporter:

Instead of picking apart everyone's posts maybe you can write up a little piece on billet vs. forged.



Seems to me I have written lengthy posts on the cast vs. forged vs. billet threads on multiple occasions, on multiple boards. I am not going to do it everytime the topic comes up.
Geohans
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Posted: 12/6/2008 3:15:24 PM EST
Battle, how about requesting a sticky? I agree it would be very useful.

use the archives, cut/paste, but this would be valuable.
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Posted: 12/22/2008 7:24:16 PM EST
How bought a link?
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Keith_J
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Posted: 12/22/2008 7:43:46 PM EST
AGNTSA? From an earlier thread (AHEM, Mods, a tack?)

http://www.ar15.com/forums/topic.html?b=3&f=118&t=413585

Forged, any day, will be stronger on a lower. Why? The weakest part is the buffer tube ring at the rear of the lower. Here, the forged lower has a flowed grain structure optimized for the area.

Hogged out of bar stock, the grain of the metal is like that of straight-grained wood. Entirely wrong for the part. With good quality 7075 aluminum, you can get away with it. But how many are actual Kaiser/ALCOA/Renyolds with Certified Mill Test Reports? And how do you know the grain direction? You are at the mercy of the machinist who may or may not know about aluminum microstructure.

Now let us look at the typical Mill Test Report for aluminum. Firstly, there is the chemical analysis. This tells us the alloy. Then there is the temper designation. We want T6. No need in having to send it out for heat treat as then more testing. Then we have tensile testing.

Now for the fun part. Tensile testing. This part of the MTR will have at least two, if not three tensile specimen axes. Not the Paul Bunyon tree felling implement but the direction in which the samples are loaded. There will be specified minimums, yield point, enlongation and ultimate tensile strengths reported. For sheet products, there is typically only two tensile coupons and a shear but for plate/bar, there can be three tensile tests. Since the lower is subjected to triaxial stress with associated moments, it would be a good idea to insist on knowing these properties.

But in a forging? Part of the quality process is complete tensile testing of the rough forging and sample coupons have been taken from a representative part.

Since non-destructive testing on aluminum is limited to RT/UT/PT and all but PT are specialized practices, buying a receiver hogged out of bar/plate is a gamble. I would suggest a copy of the mill test report.

And despite the over misuse of the term "billet". I continue to call these plate machinings. Why not billet? Because a billet is a raw mill product without any wrought processing. Billets are technically CASTINGS and not what the machine shop or even forging plant uses as raw material. Forgings are made from BAR STOCK which is a wrought product form.

Anodizing does NOTHING to strength. It is brittle, being a form of aluminum oxide not unlike that common abrasive on sandpaper. It is flat, solid ceramic made from the aluminum itself so it has great adhesion.

In the M16 series, the upper only holds the pieces of the rifle together and forms a guide for the bolt carrier. Because the only real sliding force contact is the carrier key's reaction to bolt locking/unlocking torque, this is the only real wear area. The sliding forces of the carrier are very low, representing only the misalignment of the carrier. Since the carrier key slot is protected from dirt, this causes the carrier's rails to exhibit the greatest wear even though steel is much harder than aluminum. The anodization polishes the rails slowly. In proper treated uppers, a layer of moly disulfide dry film lube keeps this wear minimal.

In fact, hard anodization can form surface crack propagation, lowering fatigue life. But this is not significant in the M16 series as there is sufficient ductility and the receivers are subjected to very low cyclic stress.

Hard anodization is a durable finish, resistant to most abrasion from normal "sling type" wear. But being brittle, impact with hard surfaces will cause failure. The military refinishes with moly disulfide dry film lubricant, all over.
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Croft32
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Posted: 10/30/2009 8:39:36 PM EST
For those of you who received an email from Ranier Arms about their billet uppers and the grade of aluminum used, what do you think about it?
chadwick76
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Posted: 10/30/2009 9:31:17 PM EST
first pic?



any day of the week!!!IMHO
Do you believe me, or your own eyes?????
Hendricks5150
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Posted: 10/31/2009 3:34:28 AM EST
I always thought that billet was stronger. It does look better too
Shooting stuff is fun... And thanks diestone for the avatar

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