DSA ZM4 Forged 7075T6 A3 AR15 Upper Receiver
 

$275

AR-15 upper,minus bcg.Good price although 1/9 twist and not chromed lined.I always try to buy made in usa,unlike some traitor's.............:coolbeer:

Forged 7075T6 A3 Flattop Upper Receiver
- Forged Front Sight Base with Bayonet Lug
- A2 Flash Hider
- 16 Inch 5.56mm NATO Nitride Treated Chrome Moly 1:9 Twist ZM-4 Barrel
- M4 Style Handguards
- Aluminum Delta Ring
- M4 Style Feed Ramps
- Upper Half assembled as shown, no bolt, bolt carrier or charging handle included.

Manufactured by DSA - All Parts U.S. Made!

http://www.dsarms.com/DSA-ZM4-Forged...info/DSZM4CBU/

Re: DSA ZM4 Forged 7075T6 A3 AR15 Upper Receiver
 

Very interesting. I have an AR-15 and I never noticed what alloy the receiver was made from before you mentioned it in this thread. It surprises me that it's 7075 as that alloy is not as shock resistant as some other "aircraft grade" aluminum alloys. 7075 does have very high strength. When I looked it up I read that the earliest M-16's were made from 6061, which is the alloy I would have guessed. The source claimed that the 6061 receivers were corroding rapidly under field conditions. I find this difficult to believe because that alloy is used in everything including a lot of gear that sees harsh use. I would believe that it could possibly be subject to a little more wear and deformation but surface treatments could play a role too.