AR lower reciver

[Crazy Ivan]

I have seen that many of the lower recivers on the AR-15 is made from alumina. I thought that was to soft for use in this kind of equipment.But it doesnt seam like that.Is it made from some specifik kind of alumina or???

Why aint they made from some sort of iron to make it stronger?

Are there different kind of lower recivers (Im refering to stripped lower recivers only)?

Hope to get a reply from someone.

[Imshootin]

They're made from an aircraft grade aluminum alloy (7075 T-6 I believe) so there are other metals added plus it is heat treated a certain way and eventually annodized. It is tough enough for the job.

[Crazy Ivan]

Thank you for that answere.
Especially the "aircraft grade aluminum alloy (7075 T-6 I believe)".

[remingtondude58]

Are there different kind of lower recivers (Im refering to stripped lower recivers only)?

There are lowers in 9mm and probably other calibers as well. Plus they come in a variety of finishes from a variety of companies. Those are the only differences I know.

[Joeywhat]

I'm sure you could get one made of iron if you asked for it...but I'm not sure why anyone would want to.

[RifleGuy]

Ivan, most modern production vehicle engines are made from aluminum; block, cylinder heads, pistons, etc. Many modern aluminum alloys are stronger, but much lighter, than steel.
The aluminum pistons in an engine are subjected to tremendous stresses and temperatures near 1000 deg. C, but will last 100,000 kilometers easily.
Also, with the AR design, the majority of the stressors are confined to the upper receiver.

[Crazy Ivan]

Even if they are made in " a variety of finishes" they are made with the same messurements to fit as long as the calibre is right according to the upper recivers, or??
The reason i ask is because there seams to be different suppliers of all parts.So it has to fit anyway, or is it possible they would need some "adjusting" to fit if parts comes from different suppliers???

[Joeywhat]

You'll find that the vast majorities of uppers and lowers will work with little to no problems. Some might be "looser" then others, some might be real tight. They do make plastic inserts that can cure a loose upper/lower fit.

[Crazy Ivan]

Thanks.

I must say that Im impressed by the knowledge and the fast replies here.Its make it so much more fun when ppl who know are willing to share their knowledge.

[JDG]

Forged aluminum is very hard! I had to drill lube holes in a motorcycle piston skirt once, and was shocked how hard it drilled.

[the_grimace]

Material Data Sheet

http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA7075T6

[Crazy Ivan]

Since I dont have a life I spend TOOO much time (of the little freetime I have) infront of the computer or with my projects.

I just wanted to show this link for anyone who like to build his/her own lower reciver.
http://www.ar15plus.com/default.asp

Accordning to the information I seen on several places its legal to buy a lower reciver thats only finished up to 80% without any FFL-dealer neccessary.
The bad side is that it doesnt seam as if its legal to sell the weapon after you buildt it.But i leave that for the leagal beagel thread for another day.

But now to another question that arise just after I read about the different recivers.It seams as if they come in a variety of materials. So does it really matter what material one choose?
Of course titanium are strong etc...But is it really neccessary?
After all, as RifleGuy wrote, "Also, with the AR design, the majority of the stressors are confined to the upper receiver.".
So it would be nice to hear the opinion from you all again in this matter of the importance of the material of the lower reciver........

[the_grimace]

Hey Crazy Ivan,

found another sight you might like that has to do with building your own AR15.

http://www.ar15pro.com/category/262-AR15_Lowers.aspx

Some info about the 80% receiver

http://www.acmearms.com/80percentfaq.php

To answer your material selection question. There are many choices out there. Most of the are Aluminum of some varity. They can also be cast, forged, milled, etc. Every option has it's strengths/weaknesses.

Hope that helps with some of your questions and good luck with the build!

[Mongo]

Companies have even made AR lower receivers from polymer, like the glock frames. The lower on an AR is not a highly stressed part.

[Stazi]

The lower reciever on an AR doesn't see anywhere as much stress as the upper receiver does, and even that is Aluminum.