My last year in the Army was issue a brand new m4 and brand new ACOG. I had a bad spill and fell on the rifle. The 30 round mag in one of my ammo pouches was dented badly, and the ACOG was gouged up pretty bad.


Still held zero and was made of 7075 aluminum.

Any other optics made of this expensive sht?

No

I wonder if all the Trijicon optics are made of such stuff.

The scope manufacturer might be able to answer that question.

That is one funny post. "expensive" ? You can't be serious. The price of 6061 is about $1.50 per pound and 7075 is about $2.50 per pound. The selection of the type of aluminum for a riflescope encompasses a lot more parameters than just price and "strength". There's machinability, longevity, resistance, plating, finish, appearance and on and on. Even if a scope had a body made of titanium, the choice of materials for the insides and how they are designed and assembled have a lot more to do with retaining zero than anything else.

Don't think any scopes are

Lots of scope rings made from 7075….

Properties of both alloys can be varied (controlled) greatly with various temper designations. Certainly, 7075 is a great alloy for many applications, but there are multiple alloys that could specified to be more than sufficient for scope tube applications. Wall thickness is another key contributor to the strength of the tube.

I don’t recall seeing many scope brands advertising the alloy their tubes are made from.

No idea about scopes, but all the pack frames I carried in the 1970’s were made of 7075, and pack stays in later internal frame packs through the 80’s and 90’s were usually 7075. Always struck me as tough but still had some flex. Seem to remember it’s an aircraft grade aluminum.

We used to buy odd lot sheets of 7075 from the Boeing surplus store in Kent Washington. We used it for the bottom (floor) of our race cars. It held up well. Was not nearly as ductile as 6061.

Just what the hel! is " Aircraft Grade Aluminum "?
90% of the aluminum i see used in aircraft is 2024. I can promise you it isn't used in scope tubes.
The term " Aircraft Grade Aluminum " is probably the most ambiguous and over- used description all of manufacturing.
🤭

Most all aluminum arrows are 7075, known for straightness tolerance and durability....but certainly can bend fairly easily.

Nope. It's 2nd, behind: "Mil-Spec".

Except in the case of 7075 it's pretty accurate.

https://en.wikipedia.org/wiki/7075_aluminium_alloy

"7075 aluminium alloy (AA7075) is an aluminium alloy with zinc as the primary alloying element. It has excellent mechanical properties and exhibits good ductility, high strength, toughness, and good resistance to fatigue. It is more susceptible to embrittlement than many other aluminium alloys because of microsegregation, but has significantly better corrosion resistance than the alloys from the 2000 series. It is one of the most commonly used aluminium alloys for highly stressed structural applications and has been extensively used in aircraft structural parts.[2]

7075 aluminium alloy's composition roughly includes 5.6–6.1% zinc, 2.1–2.5% magnesium, 1.2–1.6% copper, and less than a half percent of silicon, iron, manganese, titanium, chromium, and other metals. It is produced in many tempers, some of which are 7075-0, 7075-T6, 7075-T651.

The first 7075 was developed in secret by a Japanese company, Sumitomo Metal, in 1935,[3] but reverse engineered by Alcoa in 1943, after examining a captured Japanese aircraft.[4] 7075 was standardized for aerospace use in 1945.[5] 7075 was eventually used for airframe production in the Imperial Japanese Navy."

Uses

The world's first mass-production usage of the 7075 aluminum alloy was for the Mitsubishi A6M Zero fighter. The aircraft was known for its excellent maneuverability which was facilitated by the higher strength of 7075 compared to previous aluminum alloys.

7000 series alloys such as 7075 are often used in transport applications due to their high specific strength, including marine, automotive and aviation.[7][13] These same properties lead to its use in rock climbing equipment, bicycle components, inline-skating-frames and hang glider airframes are commonly made from 7075 aluminium alloy. Hobby-grade RC models commonly use 7075 and 6061 for chassis plates. 7075 is used in the manufacturing of M16 rifles for the U.S. military as well as AR-15 style rifles for the civilian market. In particular high-quality M16 rifle lower and upper receivers, as well as extension tubes, are typically made from 7075-T6 alloy. Desert Tactical Arms, SIG Sauer, and French armament company PGM use it for their precision rifles. It is also commonly used in shafts for lacrosse sticks, such as the STX sabre, and camping knife and fork sets. It is a common material used in competition yo-yos as well.

Due to its high strength, low density, thermal properties, and its ability to be highly polished, 7075 is widely used in mold tool manufacturing. This alloy has been further refined into other 7000 series alloys for this application, namely 7050 and 7020.
Aerospace applications

7075 was used in the Space Shuttle SRB nozzles, and the external tank SRB beam in the Inter-tank section. The forward- and aft skirt as well as the Interstage of the S-II, the second stage of the Saturn V was made from 7075.[14]
Applications

Aircraft fittings
Gears and shafts
Missile parts
Regulating valve parts
Worm gears
Aerospace/defense applications
Automotive

Don't forget the "Machined from Billet Aluminum". As in "Billet Aluminum Tactical Special Ops Mil-Spec Mono-Pod" marketing phraseology.

Billet

7075 is very strong but somewhat brittle.
2024 is what all aircraft sheet megalomania is made of. (Actually clad with pure aluminum) 2024 uses copper for main alloy. Copper alloy very susceptible to intergranular corrosion. But it's strong and handles flexing well.
It machines great but doesn't anodize well. Mil-spec is a real thing. There's actual specifications spelled out.
There is NO specification for " aircraft grade "
I think a turd could lega be called aircraft grade

Zeppelin spars - 2024 uses copper (duraluminium )

I was talking to an AR15 manufacturer one time and asked if he ever used 7075 for lowers. He said they're was no need, lowers are successfully made from ploymer, 6061 is more than strong enough. He agreed to make me one from 2024 but we couldn't source a big enough chunk. I figured it really would be aircraft aluminum then!

I dunno if there's different types of 7075 aluminum but ALL the dogsled runners on iditarod race sleds are made of 7075 extrusions designed to take quick-change uhmw runners.


In areas like the burn (low or no snow), along the thousand mile race route, you can see in footage of these fkn sleds getting pounded. The aluminum in those runners flexes very well. Very rarely will a racer brake a runner, but it does happen.


I had QCR 6061 rails and that fkn garbage was cracked after a single season.

I've always avoided 7075 for projects simply because you can't really weld it...at least I can't using normal methods.

I'd missed Brad's excellent explanation until now so I erased by babbling. I will leave the link.



https://esab.com/us/nam_en/esab-uni...g-the-aluminum-alloy-designation-system/

The vast, vast majority of AR uppers and lowers are made of 7075 T6. Both billet and forged.

I don't know of any AR upper or lowers made today out of 6061. It's very marginal in that application.

There are at least 5 shops in the Phoenix area making lowers. ALL are 6061. All of them. 7075 is b twice as expensive, harder to machine and doesn't anodize quite as well.
It is certainly stronger but Titanium is stronger yet...

As I said the vast vast majority of AR uppers and lowers are 7075.

Every major manufacturer from Anderson to Zev uses 7075.

Colt, Sig, Ruger, BCM, DD, Aero, PSA, POF, LaRue, Geissle, FN, Noveske, ect.

Could there be a low end shop using 6061. Sure.

But again 7075 is the industry standard for ARs and has been from the first Colt TDP.

All my ARs are 7075 and it anodizes great.

List the 5 shops using 6061.

POF, Quentin Defense,Gibbs...

Not this really makes any difference, but I always avoid 7075 for projects simply because I can't weld it...

Hi-Lux claims to use 7075-T6 in one of their scopes.

ETA - There are RDS made of 7075, but am assuming that you were asking about conventional magnified scopes?

Yes:

https://hi-luxoptics.com/products/hi-lux-pr5-5x-25x56-ffp-rifle-scope?variant=43970323415253


4th point, good find.

POF confirmed to me today that they do not use 6061.

Claim to use a proprietary alloy but absolutely not 6061.