Machining Question



nice save.
Now it has "bearings".
I was examing some sort of German rifle and pretty much any sliding parts had actual bearings, including the ends of torsion springs- they had little metal sleeves acting as rollers. They must have had lots of spare time to come up with all of that.
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The original ARs back in the Vietnam timeframe had 6061 forgings. They had some trouble with corrosion from guys' sweat, so 7075 was the next step. Some of the early clone lowers were castings, some so bad that they broke when the rifle fell over onto the floor. Stoner's genius was you could probably make a lower out of recycled bubblegum and have it work as long as it stood up to the fire control springs' pressure. So 6061 or 7075, doesn't make much difference except when anodizing. .223 recoil is about nil, the forgings/castings don't directly take chamber pressure so yield strength is irrelevant for most civilian uses. If you intend on beating up bunnies or whacking coyotes with the buttstock, it might make a difference.
Stan
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On Mon, 8 Apr 2013 13:43:26 -0700 (PDT), Stanley Schaefer

Something is strange there. I'd have to dig out my ASM book to check, but 7075 has low corrosion resistance overall and is not recommended at all for marine environments (or salty sweat, one would assume). 6061 is somewhere in the middle.

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On 4/8/2013 4:06 PM, Ed Huntress wrote:
Snipped - just to show it's technically possible...

I wondered about that too.
What's the story here?
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wrote:

Ok, from ASM's "Metals Handbook," 9th Edition:
7075 is more corrosion-resistant thant 2024 but worse than any other wrought alloy.
The zinc is no help, but it's the copper that's the big problem, as it is with 2024. However, the copper improves resistance to stress-corrosion cracking.
So in terms of general corrosion, 7075 kind of stinks. 6061 is good even in marine environments -- although some 5xxxx and 1100 are better.
--
Ed Huntress

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On Mon, 08 Apr 2013 20:00:59 -0400, Ed Huntress wrote:

Which of 7075 and 6061 has better corrosion resistance when they are anodized?
--
jiw

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On Tue, 9 Apr 2013 00:20:35 +0000 (UTC), James Waldby

The only data in my ASM handbook is for anodized samples exposed to a salt-air environment. Again, 2024 and 7075 came our worst. All others, including 6061, did better.
There also is an anecdotal comment that anodizing does not improve the stress-corrosion characteristics of 7075, and may make it worse.
--
Ed Huntress

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Richard wrote:

Current Mil spec is 7075 - T6
The original design called for either a 6 or 7 series alloy. The 6 was cheaper and easier to work with so that was what ended up being used. The problem is that between corrosion and thread deformation the spec was re-written to 7075 - T6 being the "correct" alloy to use.
I have shot both and other than knowing the alloy due to the makers you couldn't tell any real difference. 6061 is still used by a few companies and with the design of the AR the strength in Civilian use isn't an issue.
However if you plan on needing to depend on the rifle in real combat where you may be using it as a club, hammer or whatever, the 7075 has the edge with regard to wear and tear.
I have used both forgings and solid billet as a starting point. With forgings you are limited as to what you can add/subtract. With billet you can have fun. I machined in a solid trigger guard, milled my logo in 3D on the side, and a few other tricks.
--
Steve W.

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wrote:

Could you machine one out of a stainless steel block?
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Gunner Asch wrote:

Already been done. There are a few companies that already sell stainless lowers.
I did one out of 416 just to see what it took. It will be the only one I ever do as well. It machined very well but even when I thinned areas down to reduce weight it's still pretty hefty. Does make the .308 a lot nicer to shoot though. I have been tossing around the idea of making one out of steel though. Thinking of areas like the sides of the mag well for skeletonizing...
Anyone with a mid sized mill can handle the job. If you buy some guides you can even use a good drill press!
--
Steve W.

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wrote:

Id not mind having a lower someday. Though given the prices of the upper Stuff..it would likely remain a door stop.
ARs are quasi legal here in California..but they have to be neutered with a 10 rd mag and a bullet button etc etc
Gunner
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wrote:

Bullet button?
Remove 333 to reply. Randy
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Randy333 wrote:

Kali semi-auto guns are supposed to have "fixed or not readily removable magazines" So the bullet button was born. Instead of the normal magazine release there is a small release button that requires the tip of a bullet or similar to depress.
http://bulletbutton.com/
--
Steve W.

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wrote:

If a tool is used to remove the magazine..by California law..its not a "detatchable magazine equiped weapon"
Browse: Home / United States Takes The Gold! / Featured, News and Headlines / The Deadly Bullet Button The Deadly Bullet Button
Posted by Toni on September 8, 2012
Assault weapons are banned in California. However, gun manufacturers have found a loophole that allows gun owners to easily convert a rifle into an assault weapon. It is a feature known as a ?bullet button,? that enables the firearm owner to use a bullet or other pointed object to quickly detach and replace the weapon?s ammunition magazine. The button is recessed, preventing finger manipulation. However, by the use of something such as a bullet, or something that can depress the recessed button, the rifle can be converted into a semi-automatic assault weapon.
One rifle being manufactured by Smith & Wesson is the MP150RC which lists: a fixed magazine and bullet button, compliant for sale in California. This weapon has a 16? barrel with a 10-round magazine clip that conforms to California law. With the ?bullet button? allowing the magazine to be easily detached and replaced enabling a quick reload that California?s assault weapon law sought to ban.
The regulations banning assault weapons define a detachable magazine as ?any ammunition feeding device that can be removed readily from the firearm with neither disassembly of the firearm action nor use of a tool being required.? A bullet or ammunition cartridge is considered a tool. Magazines, or the storage areas that allow for repeat firing, that can be removed by a normal push button in combination with features such as a pistol grip and telescoping stock, are banned in California. The law essentially requires magazines to be removed and replaced with a tool, in order to slow down the process of reloading.
The sales of bullet button conversion kits in California are only part of the problem since assault rifle manufacturers are now marketing so-called ?California compliant? firearms with factory-installed bullet buttons. California now has the potential to become flooded with bullet button-equipped weapons that undermine California?s assault weapons law.
SB 249 prohibits the manufacture, transfer, or possession of conversion kits but does not address the growing problem of factory-installed bullet buttons. Providing the necessary language to prevent challenges is time consuming, therefore it has been suggested that since regulations are allowing bullet button-equipped weapons, the issue would be best addressed through the regulatory process.
Clearly, the bullet button/detachable magazine problem should be fixed. For a detailed explanation of the bullet button, see the YouTube video below.

http://www.youtube.com/watch?feature=player_embedded&v
VvMZKTCW8
Laugh laugh laugh
Gunner
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On 04/09/2013 06:09 AM, Randy333 wrote:

California prohibits (most) detachable magazines, so people work around this by using a "fixed" magazine that requires a "tool" to detach the magazine.
It so happens that the mechanism some people use fix the magazine is with a fastener that requires a tool that is of the same shape as a typical bullet, ergo a "bullet button".
Jon
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On 4/8/2013 11:19 PM, Steve W. wrote:

What does that do to the weight???
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wrote:

It would center it nicely..and by the time folks get done putting all the lasers, launchers and other sundry bullshit on them...shrug...a steel lower really wouldnt be noticed too much.
Gunner
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I enjoy watching clowns with laser sights at the range. They are good if you have a spotter and are trying to tame flinch.
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Richard wrote:

Adds about 8 oz. to the bare lower compared to a "normal" lower.
--
Steve W.

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wrote:

Half a pound isnt shit.
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