Stripped Lower - 7075 or 6061? [Archive]

M.Bailey

07-09-16, 20:09

Hi everyone. I purchased a stripped lower today from my LGS. It's their shop brand - they get the forgings and finish 'em up themselves. The lower looks good to my (untrained) eye, but I am just curious if it is possible to tell if it is 7075 or 6061.

It has a Cerro Forge mark (keyhole). Does anyone know if Cerro makes both kinds?

Thanks for the advice.

lysander

07-09-16, 20:18

Got an atomic absorption spectroscope?

Or, you can take a welder to it. If it welds nicely its 6061.

Other than just knowing, there is little practical difference, in this application.

The original design was designed to be made from 6061.

Ryno12

07-09-16, 20:41

Did you try asking the LGS you purchased it from?

M.Bailey

07-09-16, 21:19

Did you try asking the LGS you purchased it from?

I did. I have no reason to not believe him. Just curious to know if there is a way to tell.

MegademiC

07-09-16, 22:15

As lysander said, a digested sample and an aa is real quick and easy if you have access to one. A newer xrf is nondestructive and may be able to tell the difference also, but I don't know if the alloy difference is within the variation of most xrf devices or not, as I don't know the difderence...

Edit looks like 7075 has 5% Zn so you could just xrf for that. 6061 has <1%.

lysander

07-09-16, 22:32

As lysander said, a digested sample and an aa is real quick and easy if you have access to one. A newer xrf is nondestructive and may be able to tell the difference also, but I don't know if the alloy difference is within the variation of most xrf devices or not, as I don't know the difderence...

Edit looks like 7075 has 5% Zn so you could just xrf for that. 6061 has <1%.
You would still have to cut through the anodizing an get to the base material, technically "destructive"

rjacobs

07-09-16, 23:40

I didnt realize anybody was actually still making forged 6061 lowers except for the goofy ass 80% crowd.

If its a Cerro im going to say with 99% certainty that its 7075.

jamey.kish

07-10-16, 09:49

Hi everyone. I purchased a stripped lower today from my LGS. It's their shop brand - they get the forgings and finish 'em up themselves. The lower looks good to my (untrained) eye, but I am just curious if it is possible to tell if it is 7075 or 6061.

It has a Cerro Forge mark (keyhole). Does anyone know if Cerro makes both kinds?

Thanks for the advice.

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