I've always wondered this but never found out why.  Why are there commercial AND mil spec buffer tube sizes.  Wouldn't it be easier for everyone if it was only mil spec?

 

Cost doesn't seem to be the issue since they are both about the same price.  Does not compute. 

Cost of spec'd aluminum.  Mil-spec uses aluminum to grade 7075.  Commercial uses 6061. Because of the lower tensile strength the tube must be heavier to provide a similar strength.

 

Read these posts.

http://www.ar15.com/forums/t_3_118/615043_6061_vs_7075.html

Cost of spec'd aluminum.  Mil-spec uses aluminum to grade 7075.  Commercial uses 6061. Because of the lower tensile strength the tube must be heavier to provide a similar strength.

 

 

Sounds logical, but then why are they the same retail price?  Are manufacturer's just marking the commercial up more?  And why would any consumer want to purchase a commercial knowing that it is a lower grade product?

I added a link to my original post. It should explain it all.

The cheaper milspec tubes are 6061 also. The good ones are 7075.

Cost of spec'd aluminum.  Mil-spec uses aluminum to grade 7075.  Commercial uses 6061. Because of the lower tensile strength the tube must be heavier to provide a similar strength.

 

Read these posts.

http://www.ar15.com/forums/t_3_118/615043_6061_vs_7075.html

Not always.  Those really cheap milspec tubes on the market are typically made from extruded 6061, not forged 7075.  The "milspec" they refer to is the extension's diameter and nothing more.  Typically, they'll be extruded 6061 with cut threads.  The ideal receiver extension is made from forged 7075 with rolled threads.  Otherwise, a 6061 with rolled threads.