What is it?

[Earl]

I am new to this forum and new to ar platform so be please excuse rookie questions.

I purchased 308 ar from a local shop, it has an Anderson Manufacturing AM-10 lower but I don't know how to tell what the upper is. The only stamping I can find on the upper is a keyhole symbol on the right rear side. It doesn't have a dust cover for the ejection port and it doesn't have a forward assist.

I believe it to be an assembled rifle and not one purchased complete but I don't know this for sure, I have attached a picture of the upper receiver.

One of the reasons I want to know is that I would like to change the barrel and want to make sure what I buy will fit.

Thanks 

[Belt Fed]

Keyhole = Cerro Forge

 

https://www.cdsarms.com/upper-forgings/

[Lowlander]

On 4/13/2020 at 5:49 PM, Earl said:

I am new to this forum and new to ar platform so be please excuse rookie questions.

I purchased 308 ar from a local shop, it has an Anderson Manufacturing AM-10 lower but I don't know how to tell what the upper is. The only stamping I can find on the upper is a keyhole symbol on the right rear side. It doesn't have a dust cover for the ejection port and it doesn't have a forward assist.

I believe it to be an assembled rifle and not one purchased complete but I don't know this for sure, I have attached a picture of the upper receiver.

One of the reasons I want to know is that I would like to change the barrel and want to make sure what I buy will fit.

Thanks 

Looks like an Anderson AM10 upper to me. So it appears to be the same make/model as your lower. It also appears that your handguard is not an Anderson handguard. If I am thinking right, the Anderson AM10 has a bit different rail height than anyone else, so to get the upper and handguard top rails to match up properly, you'll have to go with an Anderson handguard. That's why there is a height difference between your upper rail and the handguard rail.

But your upper does appear to be the matching AM10 upper that goes with your AM10 lower. If the height difference between the upper rail and handguard rail doesn't bother you, then it's not that big of a deal. I'm not a huge fan of the Anderson handguard, so you may have a more functional rail with what you have on there despite the height difference.

Also I'm pretty sure the dimensions on the AM10 upper/lower are proprietary. So they really will only mate up with other AM10 uppers/lowers. I'm new here so some of the other guys here may have different info than I do? Back when I was looking at builders kits that was one of the things that steered me away from Anderson...

Other than that, you should be able to swap in any DPMS/SR25 pattern barrel onto the upper as I understand it. Most 308 AR barrels are this pattern so you should have no issues finding what you want there. 

Hope this helps and feel free to correct anything that's incorrect, I'm new here too like I said...

 

ETA: As Belt Fed posted, the keyhole is just a forge mark. Cerro Forge is pretty common marking, the machining is done by each manufacturer.

Edited April 17, 2020 by Lowlander