Is this the proper material for an AR15 upper receiver?

Question

"4150 chrome moly vanadium steel receiver"

http://www.aimsurplus.com/cgi-bin/sh000001.pl?REFPAGE=http://www.aimsurplus.com/acatalog/firearm_requirements.html&WD=cmmg&PN=CMMG_.223_5.56x45_AR15_M4_16_Complete_Upper_Half.html#a232#a232

I thought the receivers were supposed to be made of forged aluminum alloy... not steel. Isn't that grade of steel what is supposed to be used for the barrel? Isn't that being used on the receiver instead of aluminum alloy going to make it pretty heavy?

Answer 1

I think they made an error in their description, 4150 is the correct steel for the barrel.  The correct material for the upper and lower receiver is 7075-T6 aluminum alloy.  Some makers use 6061 aluminum for civilian AR-15 rifles, but the U.S. Military specifies 7075 in the contracts for the M16

Answer 2

I can assure you that it is a typo.  That material and description is what the barrel is made of.   The receiver is definitely aluminum.  CMMG is excellent and that is an excellent value for that upper.  

Answer 3

Your link doesn't work.

Answer 4

It might be a typo, email or call them and ask about it. They'll be more than happy to explain anything in the discription to you.

I live about 20 minutes down the road from their shop and they're a great bunch of people. If you call ask for Bryan, he's very knowledgeable and more than willing to chat with customers.