I had a Cerro forged (keyhole) Anderson Mfg. Lightweight Upper (without forward assist or dust cover).  That upper worked perfectly and fit great.  I recently tried Anderson Mfg newer batch of Lightweight Uppers but they are forged by Brass and Aluminum Forge (square box) and do not fit well at all.  Seems like the uppers were milled out of spec.  

Anyone know a source of the older Cerro forged lightweight uppers?  I need 25.

Anyone else having trouble with the new Brass and Aluminum forged lightweight uppers from Anderson Mfg?  

I am just wondering if I got four out of spec upper or they were all out of spec.  I have tried them on other lower with issues, but they seem to work fine with most Anderson lowers.  

Anderson Lightweight Upper

Aim Surplus

Call Aim Surplus and ask what forge marks are on the uppers they have.

I did.  They don't have any of the Cerro forged upper anymore.  Seems Anderson changed forges for that particular upper.

I don't think the forge is the problem.  They just provide the raw blanks.  It's the machine shop that cuts everything out and controls the final product.  My guess is they got a better deal from a different forge and with the prices of AR parts these days maybe QC is getting a little lax.

Obviously QA is the issue on this one.  Surprisingly, they are the only one offering this upper configuration.  I may have to go with Aero Precision upper with the dust cover.

Aero Precision w/no Forward Assist $50

I can't tell you if these are as light as the Anderson's, but maybe a option for you.

Not my pic but I got one like this a couple of years ago from Anderson. I wish I'd bought more.

You can get that one from Aero precision

What exactly about them do you think is out of spec?

Aero has them without forward assist but they have the case deflector. The Anderson upper has neither.

Your concern over the forging source is surprising. The finish machining is really the only consideration. What possible difference could the forge have over final dimensions?

Yeah, I only bought one thinking "I can always get more."

Majorcollins.....They didn't fit well on the receivers when the take down pin tried to go in...binding.   The mating of the upper to the lower seemed too tight as it pivoted down onto the lower.  By the time the takedown holes lined up you could see the holes didn't match up.  The upper was higher than the lower.  I milled one out and it was a significant amount of material taken off to be"in spec".  Also when pivoting closed, the rear lug would touch on the back of some receivers (the area rear of the lug)

Centroid.....No, I am not worried about the forging....I am identifying that the Anderson uppers Cerro forgings were in spec, therefore I was trying to locate a batch of those forgings because I know they worked (although it is conceivable that the next batch of cerro uppers from Anderson could have been put of spec also).  Anderson possibly outsource the uppers...who knows.

Grondike...You are correct, the Aero do have the brass deflectors with the dustcover mount point.  I was just trying to find an upper with just deflector, but no FA or Dustcover.


UPDATE: Got a call back from Anderson.  Two of the three sent back seems ok when fitted to their lowers, but one would fit well on one of there lower, but not on another of their lowers which baffled their tech.  They are sending me three new uppers.  Will advise how they are when I get them.

I'm not sure you are fully understanding me, so allow me to explain further. Every dimension on an upper receiver forging is over sized. The manufacturer of the finished receiver machines the tolerances you have concerns about. Why worry about what forge the part came from? Your argument is with Anderson, not Cerro or B&A.

Note the image below of a B&A forging. How could they have any responsibility for the fit to your lower?

Centroid....Thanks for your input.  I fully understand.  I think you missed my point.  If anderson milled the cerro forgings in spec and they worked perfectly on my preferred lower but the new B&A forgings milled by Anderson were not in the same spec, I would merely look for the old batch of cerro uppers if there were any around.  As the forgings are over sized, perhaps the difference in the two forgings somehow cause the milling process to alter their CNC programing (i don't know just a hypothesis).  Either way, my intentions of this posting was to possible find a batch of Anderson Cerro forgings Anderson Lightweight uppers that were still out there I could purchase for my builds and not go back and forth with Anderson on some B&A forgings that work and some that don't.  Or possibly find some other manufacture that are producing the same thing.  

If all else fails, I will go with Aero Precision Lightweight Upper with dustcover and no-FA.  I can get them for the same price.

I contacted Anderson's Project Coordinator in May of last year and he said they had no plans to make any more

Maybe they can be persuaded to make a run if there was enough interest

Well, that is interesting news.  I guess there really isn't any incentive in going with them now.  I may have to just go with a different upper in the end anyway.