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Discussion Starter · #1 ·
Was searching the net on the ACR's upper composition and came across a few sites that stated the upper is extruded rather than forged. What gives? Also, anyone here know whether or not the aluminum is 7075 or 6061? I'm assuming 6061 if it is extruded. If that be the case, then I'm pretty disappointed that BM would cheap out and go with a softer material and an extrusion process and still charge a premium. Maybe I should have gone with a KAC SR-25 instead... :rolleyes::rolleyes:
 

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Take a look at my thread in the gallery "The early days" and you'll see a raw Masada upper receiver extrusion. Using an extrusion for this receiver saves money because you're not having to start with a block and mill away probably better than half of the material. The extrusion supplies the basic shape right out of the gate. If I'm not mistaken the SCAR receiver is extruded as well.
 

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I bought it for the improved ergonomics and the magpul design and the modularity. I don't care if they made it out of cheese. As long as it lasts a few hundred thousand rounds or so, that's all I can reasonably see putting through it.
 

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Discussion Starter · #4 ·
I bought it for the improved ergonomics and the magpul design and the modularity. I don't care if they made it out of cheese. As long as it lasts a few hundred thousand rounds or so, that's all I can reasonably see putting through it.
Understood, and I too purchased my ACR due to ergonomics. However, I think my concern is a valid one. The US military calls for forged receivers for their M16s; not milled, cast, or extruded. I'm assuming this is for material-strength reasons. If that's the case, then why did BM go with a potentially weaker process for creating their receiver? Cost savings? Apparently, at least to me. Perhaps they needed to recoup their investment costs in R&D, molds, dies, or what have you... I'm rationalizing I know, but for the price asked, you'd think some of the savings incurred by going to a cheaper production method could have been passed in some form to the consumer.

Question - does the Remington version also use an extruded upper?
 

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Discussion Starter · #5 ·
Take a look at my thread in the gallery "The early days" and you'll see a raw Masada upper receiver extrusion. Using an extrusion for this receiver saves money because you're not having to start with a block and mill away probably better than half of the material. The extrusion supplies the basic shape right out of the gate. If I'm not mistaken the SCAR receiver is extruded as well.
Then why not go with cast if material waste is a cost-related issue ? Casting has proven to be just as strong as forging if done correctly with minimal raw material loss.
 

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after seeing how it took that exploded casing i'm not too worried about the strength of the rifle receiver, not to mention all parts that have metal on metal contact are removable/replacable and coated with melonite
 

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Extruded metals are not inherently weak. Alot of the ribs and spars of an aircraft wing are made from extruded aluminum. It's an ease of manufacturing and contiunous pieces that help with the strength of the finished product. The upper reciever is only a vehicle to hold all the parts, line up and in one place. The barrel, barrel extension and bolt group are doing all the real heavy work. The AR15 / M16 are built with the same premise. Older rifles, (M1 garand, M14, FN FAL etc.) depended on the recievers for alot of their strength by design.

As said earlier, it is a more economical process that eliminates unnecsessary machining. Both versions (BFI / Rem Defense) of the ACR use a common reciever and the SCAR is also made from an extruded upper.

The ACR upper is good to go strength wise. Actually the reciever of the ACR kaboom that has been shared on the forum looks like it held up real well. (better than some AR15 kabooms I have seen)
 

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Extruded is faster to produce a part that is closer to finished dimensions in 1 cross section than a casting, allows for a continuous (more or less) production process, costs less to make a form for, and allows for a cheaper part, faster setup and delivery, and cuts down on the amount of finish machining needed considerably.

The outer part of the reciever (Flats) is probably the same dimension it was when it left the extruder. (Rail was machined obviously.)
 

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Discussion Starter · #10 ·
Thanks for the chart VB3. I feel little more confident in at least knowing the material is 7075 rather than 6061. Is the upper coated with melonite as well or is that strictly limited to the barrel lining?
 

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Nice chart! if BM would get the conversion kits out, they could change a bunch of No to Yes.
 

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The US military calls for forged receivers for their M16s; not milled, cast, or extruded. I'm assuming this is for material-strength reasons.
Apples to oranges my friend. The shape of the AR receiver doesn't allow it to be extruded. If it did I'd have no doubt that'd been the way it would have been produced. Try not to think of it in terms of what the AR does. The ACR is its own show.
 

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Thanks for the chart VB3. I feel little more confident in at least knowing the material is 7075 rather than 6061. Is the upper coated with melonite as well or is that strictly limited to the barrel lining?
Melonite QPQ and Tennifer are all applied to alloys of steel. Aluminum is anodized for strength and finish resistance. All aluminums in industry are generally anodized. Extruded aluminums are actually very strong. Trust me. ;)
 

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iam stripping that so called anodize iam starting to think its not an anodize at all on the coyote anyway,
Agreed. The coyote seems to just be painted over the raw aluminum. However, the black one is properly anodized.
 

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The coyote is a paint finish but I think they applied a clear anodizing. I'm guessing just by the way it behaved when I engraved it for SBR markings.
 

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The coyote is a paint finish but I think they applied a clear anodizing. I'm guessing just by the way it behaved when I engraved it for SBR markings.
Yes my upper has some areas underneath the charging handle area that are not sprayed or very little over spray and its a light metallic grayish metal. Clear anodized.
Any quality real manufacturer will use anodizing on aluminum products machined, extruded, or cast. Extruded actually presses the metal into shape, somewhat like forging. Now some Hydro formed stuff I have seen would blow your mind.
Some of the airsoft crap I have seen seems to not be anodized. So bad that it was below 6000 series. Cordura nylon would wear it down like sandpaper on corners if rubbed against it with vigor.
It was definately not pot metal like zinc or tin.
 
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