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Discussion Starter · #1 · (Edited)
After completing a bare 6920 build I noticed the upper is a purple color? Does anyone else notice this on there's or is it just my lighting? I have included a pic of the new gun along with an older hbar for comparison. IMG_3265.JPG IMG_3266.JPG IMG_3330.JPG I sent it back to Colt and they made it all better! It is the picture on the bottom.
 

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The anodizing finish color on aluminum alloys could be slightly different and very hard to match exactly from batch to batch.

Even the aluminum material of for example the receivers 7075 T6 have acceptable minute material differences that would make the anodizing color difference.

I never had any Colt purple color receivers but even the black color that I had some have slightly blueish in some different lighting conditions.

With another brand that I had LMT (Lewis Machine & Tool) M4 16" barrel carbine the lower receiver, the seller told me was rejected at the factory because of finish, and the factory finished it again which delayed the shipment to me for about a month.

When I got the lower receiver with normal outdoor daytime light it looks black but in some indoor lights I could barely see it as very dark purple-black.

Even with the older Colt gray AR finish there are slight color differences and they are very hard to match exactly.

I know about it because I've been a Colt AR owner for 47 years now, also my profession of aircraft manufacturing and tool engineer for over 20 years.
 

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When my battalion got refitted with FN made M16A4 rifles (replacing what were mostly old Colt M16A2 rifles), the new M16A4s also ended up showing that same purple color on the upper receiver. We were told it was some issue with the anodizing process. You can google purple AR / M16 receivers and will come across some threads out there on it.

The rifle should be fine despite that purple color... but man I hated my purple M16A4. Hated the M16A4 for a lot of reasons, but the purple didn't help. I had no problem with the old school M16A2.
 

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A good amount of black anodizing has a purple color on many products.
I suspect it's the type of anodizing and possibly related to the type of aluminum.

I'm guessing the upper is not a name brand??
 

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Discussion Starter · #5 · (Edited)
A good amount of black anodizing has a purple color on many products.
I suspect it's the type of anodizing and possibly related to the type of aluminum.

I'm guessing the upper is not a name brand??
Whole thing is Colt. Its the one you can get without the furniture. I had just never seen nor heard of an issue like this. It doesn't bother me as its going to be a shooter.
 

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If you contact Colt about it they'll make it right.
Probably by giving you a new upper assembly.

You paid good money for a good rifle. Why settle for one that has a obvious error in the finish?
 
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