Posted: 11/8/2010 1:14:39 PM EDT
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Who makes the best upper / lowers .I was going to say best Ar but all the componant parts can be changed .so as a bare building block what would you guys choose and why ?
aggy |
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Thats what I was thinking as long as the upper/lower fit together well and are built well its all down to the choice of logo I like the spikes  I have the Spikes & I like it but it was a 2nd choice. The fit of the upper & lower is not as good as a BAR15 or fat Bobs stuff. I don't like slop between the upper & lower so a Spikes will need a wedge. No, it makes no difference to accuracy, but its movement none the less. Finish. The Spikes is supposed to be Milspec hard anodised. The upper meets the criteria. The lower...errr no, it is'nt that hard & it chips easier than what I would class hard anodised. Off to work now. Cheers |
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Type 3 (Hard Coat) is what to look for, anodised to 50 micron. Very hard (60-70C rockwell or so).
Will have 25micron penetration into the alloy substrate and a 25micron growth factor on the surface Will not chip. 7075 T6 Alloy is the mil spec material used (high strength to density), its twice as exspensive as, say 6082 T6 that actually has better corrosion resistance, but is the chosen material by the US Military. The T6 indicates the temper of the material, or heat used to strengthen the material (ie tensile strength in simple terms). There are 3 options for Uppers and Lowers, machined from Forgings, Extrusions or Billet. Billet and Forgings are nearly the same, in that both have been made from the pouring of liquid alloy, in the case of the forging its poured into a rough shape of the receivers (these can vary in quality of finish) and then has all the important surfaces CNC milled into it. Billet has to have every surface machined to create the shape as it starts life as a block of material. Extruded Upper and Lowers are generally dissliked as the extrusion (or squeezing) prosess can adversly effect the alloy molecules and stress them. Apparently. |
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Some uppers can be extruded, like the DPMS ones that some use. There is however a considerable amount of machining still req'd.
This is molten metal pressure fed through a die. Iserved my apprenticeship in this industry. Billet is a solid piece of the appropriate material that has all dimensions machined. It is the most expensive option Nd a billet lower would be around £300 and still do exactly the same job as the others. Forging is where a piece of material of approximate dimensions is stamped under extreme pressure (probably around 100 tons) into shape and final machining undertaken. This is the most cost effective way and results in the strongest items weight for weight. Casting is another method that has been done and this is simply molten metal poured into a sand mould. This is extremely fast but finishes are inferior and casting is strong in compression but not shear. Plastic breadboards have also been used, as has wood 
I have also seen lowers made from stainless and uppers made from bronze as well as steel. None was better than the other. Receiver fit and rattle is a shooter thing and us in no way detrimental to the guns accuracy, such is the advanced design of the AR platform |
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Im sorry i meant extrusion not forging
Billet machining is also different in surface detail to forged as the mill cannot replicate exactly the same details. And yes there is a load of milling to do to any method they say that the pressure and squeezing of the material through a die in extrusion stressed the material in some way, i have had no experience with this method and you would know best mark. I would say that surface finish is important as whatever the metal or alloy material used it will need protecting, any thing that chips easily should be avoided |
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As far as lowers go, avoid cast as we have seen quite a few crack and suffer from porosity. Billet machined is expensive but with modern CNC can be held to very tight tolerances. Forged lowers are the prevail of the mass produced as the die set up costs are so high. All, whether cast, billet or forged will require some machining to finish them off. Surface finish, as long as it does not interfere with function, is more cosmetic than anything else, if it looks nice and shiny then it will be more attractive to buy. Hard coat anodised will provide a modicum of corrosion resistance as will a painted finish neither will provide total corrosion protection, aluminium will corrode if not looked after. A problem with some of the billet machined lowers is that they are held to such tight tolerances that many of the mass produced parts available will not fit without some fettling.
Bottom line is that any combination of true mil spec, QA controlled, upper and lower will work well. If high accuracy is desired then free float the barrel and fit a decent trigger to the lower, most mass produced barrels will out shoot even the best AR shooters but a match barrel may give you more peace of mind. |
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I may be wrong here but I always understood that thevforging process created a uniform grain in the material that flowed with the shape of the object and was therefore stronger as compared to an extrusion process that did not. Is that right? Pretty much so, in the same way that hammer forged barrels are renouned for being tougher and lasting longer ETA: Good info here http://en.wikipedia.org/wiki/Forging |
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Aluminium is often chosen for its malleability - The vulnerability of aluminum to heat and pressure make it ideal for extruding or forging into formed, intricate shapes with ledges, grooves and interlocking parts. This allows the creation of single components, whereas other metals must be manufactured into pieces that must then be assembled to create a final product. Aluminium can be easily modified by the addition of alloys to make a final metal that is even more resilient, conductive or malleable than aluminum alone.
Extruding is most commonly used in a continuous process where the material is either pulled or forced through a forming die whereas forgings are usually stamped. In a forging operation, aluminum billets are preheated prior to insertion into the forging press. Billet and die temperatures are two of the most critical process parameters associated with the forging process. A cold billet or die prevents the forged part from flowing properly, resulting in a cracked or malformed product and excessive die wear. A hot billet or die causes surface melting during the forming process, and may cause the aluminum to to stick to the die. Properly heated billets and dies form a consistent quality product without excessive die wear, and without excessive die lubrication. Depending on how its done extruded can be stronger than forged and forged can be stronger than extruded, both are expensive to set up. Its a long time since I covered this during my engineering degree so technology has probably moved on. I do have a Stainless Steel lower on my HP Service Rifle which I think is forged, it's heavy. |
Excellent last few post gents.
For those reasons cited, we find the best strongest wheels on passenger vehicles made in the forged / squeeze cast method = best strength & uniformity of material & grain structure versus lowest material cross section ( usually !) Cheers. |
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Quoted:
Excellent last few post gents.
For those reasons cited, we find the best strongest wheels on passenger vehicles made in the forged / squeeze cast method = best strength & uniformity of material & grain structure versus lowest material cross section ( usually !) Cheers. Yep, very informative, some great willy waving going on as well. 
Andy. |
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so given the massive cost of tooling to make a uppers and lowers where are you gun plumber types getting your U & L,s from ? aggy If you're feeling adventurous... Project time... |
| I already have a spikes I was just wondering if there was anything better and why was it better . Re the project lower above I have a lathe ,good pillar drill with x travel bed but no milling macihne which is probably a good thing or I would have been locked up years ago . |
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Depends on your serial number; see here:
http://www.ar15.com/forums/topic.html?b=2&f=282&t=166787 |
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Aggy
If your aim is to buy or have built an accurate AR then don't worry about who manufactured the upper or lower just get it put together correctly, properly chambered, float the barrel and have a decent trigger. Claims that our lower or upper is the best are mostly bolloxs, be it SGC, LaRue, DPMS, Spikes or the new kid on the block, they all do the same and can all be assembled poorly. |
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i am very happy with my spikes .it ticks all the boxes and for the price i cant fault it .I like anything mechancal I always have .I also have a thing for building things so like to know all I can about it .
i can only comment on my .22 Ar, but I cant see how it can be put together poorly Its right or wrong ?? |
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i am very happy with my spikes .it ticks all the boxes and for the price i cant fault it .I like anything mechancal I always have .I also have a thing for building things so like to know all I can about it . i can only comment on my .22 Ar, but I cant see how it can be put together poorly Its right or wrong ?? Aggy, imagine if a rolls royce engine came in kit form, to do it yourself. You had two teams, one from rolls royce, and one from remploy. Who,s engine do you think would work best ?
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Aggy, imagine if a rolls royce engine came in kit form, to do it yourself. You had two teams, one from rolls royce, and one from remploy. Who,s engine do you think would work best ?
http://www.cbc.ca/gfx/images/news/photos/2010/11/04/w-qantas-engine-cp-rtxu6wh.jpg I guess the No2 (furthest away) was remploy's effort!.
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