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9/22/2017 12:11:25 AM
Posted: 11/21/2002 8:29:22 AM EDT
[Last Edit: 11/21/2002 8:29:38 AM EDT by SkaerE]
i dont really know much about aluminum. done some work w/steel and heat treating/tempering etc.

after you finish milling a 0% lower, is it good to go as far as treating?

also, what kind of aluminum do the big companies use?

Link Posted: 11/21/2002 9:20:41 AM EDT
[Last Edit: 11/21/2002 9:21:12 AM EDT by mr_wilson]
Suggest ya check out here: [url]http://www.tanneryshop.com[/url], believe aluminum used is 356(T6), but reading there will get ya up to speed on All types of 80% lowers. Mike
Link Posted: 11/21/2002 10:00:48 PM EDT
Link Posted: 11/22/2002 11:46:57 AM EDT
Castings are made of 356 aluminum, whereas the MIL SPEC forging is 7075 aluminum. The difference in these two grades of aluminum is quite significant. 7075 is at the top of the scale, 356 is near the bottom. It would be like comparing a Rolex to a Timex. Here are the facts. 356 aluminum in the T6 condition has an ultimate tensile strength of 33.0(ksi) and a Brinell hardness of 65-95 depending on the length of time it was treated. Compare that to 7075 aluminum in the T6 condition, which has an ultimate tensile strength of 83.0(ksi) and a Brinell hardness of 150. Cast lowers are not bar stock so their strength is going to be substantially less than 33.0 and 65-95. That is why the Military uses 7075 forgings, they don't want rifles shattering in a soldiers hands. To put it bluntly, if those castings were made with a grade of aluminum any lower than 356 they would be beer cans. 7075 costs about 3-5 times as much as 356. If you are doing a 0% forging the only treatment you might want to do to it is anodizeing
Link Posted: 11/23/2002 9:27:31 PM EDT
[Last Edit: 11/23/2002 9:31:00 PM EDT by pogo]
It is *easy* to break the triggerguard ears off a 80% casting, and 0% forgings are much stronger and more ductile to boot. One of my 80% receivers has a big boo-boo on the top of the trigger well, but I don't want to try to straighten it out because of how easy it is to break those ears off. I toured the Kaiser smelter and Trentwood rolling facility in Spokane. They put far more quality control effort into beer cans than airplane skin material. T-x strength is alloy dependant. 7075T-6 is not the same as, say, 356T-6. T-6 is the peak strength of the hardenability curve, with T-7, T-8 overaged and not as strong as T-6. To answer your question, they are already fully heat treated as much as is practical. EDIT: 7075 forgings is what the big boys use. Alcoa Forge makes a good bit of stuff for Colt, but AF for example won't sell you some of the goodies you find on their site as companies like Colt own the forging dies.
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