DPMS AR-15 lower receiver materials

[al1599]

Just wondering why DPMS makes 2 types or lower receivers. The T-6061 and
T-7075? I saw in Brownells the T-7075 lower and on the DPMS site it talks about a T-6061. What's the advantage and disadvantages to both and if they around the same price why would you buy the T-6061? Also thanks for your replies on my last post. seems like it is a great gun like the Glock. HAHA i know you glock dislikers aren't gonna like that just pullin' your arm. And thanks in advance for your time and efforts people it is highly appreciated. good to know there are open-minded people here.
Al

 

[havanatrader]

That's interesting. Seems that the AR-15 lowers from DPMS are made from 7075, and the LR-308 lowers are made from 6061, which is not as strong as 7075.
Seems like it would be the other way around... Perhaps one of our metallurgically inclined bretheren can explain it.

 

[browningguy]

I think, but don't know for sure, that it has to do with toughness, or brittleness of the material. We don't use a lot of aluminum but often the lower ultimate tensile strength material has better toughness properties, meaning you won't have crack initiation as easily as you would in a material that was stronger, but more brittle.

 

[GRIZ22]

Seems like it would be the other way around... Perhaps one of our metallurgically inclined bretheren can explain it.


I'm not that metallurgically inclined but it may be that the be the smaller size of the 223 requires more strength. With the 308 the more metal provides sufficient strength. My guess, I could be wrong.