I have an A2 configured rifle (I guess you could call it a clone) built by CMMG c. 2009, and I'm looking at upgrading some key components...

• They dremelled "M4 feed ramps" into both the upper receiver (after anodizing) & barrel extension.
  Their barrel is MP Inspected but not HP Tested before the inspection (not sure what that even accomplishes)
  Their bolt isn't HPT/MPI or even made out of milspec steel.
  

Sure, it shoots fine for a range toy, but I just prefer first rate stuff (I bought it when I was less aware).  So, what I'm thinking is to replace the upper, barrel & BCG (or at least the bolt) with first rate stuff.

I'm looking at using a BCM 20" government-profile barrel, which has M4 feed ramps.

The lower is black.

So, does anybody currently sell a black stripped A2 lower with M4 feed ramps that were created before anodizing?

The upper receiver and its post-anodizing feed ramps wouldn't worry me. Even Colt did the same on the 6520's.

Yeh, I have a 6520 and it looks like Colt outsourced the dremelling to the Century drunk monkeys.



I'm replacing that upper with a C7 and reworking the carbine into a 723 clone (retro lemonade :) )

The problem with dremelled feed ramps, even if done at the correct angles (which my 6520 from the factory obviously was not), is that type III hardcoat anodizing significantly hardens the surface compared to the raw aluminum, which is exposed when they dremel through the anodizing and expose white metal.  So, if the bullet tips actually impact the part of the ramp that is receiver vs barrel extension, that could develop a problem over time.  

Of course, in 2008 when I ordered it (the first Obama panic being in full swing, it took about 6 months to deliver) I didn't understand all this stuff as well as now, so on the online order form I selected "M4 feed ramps", which apparently translated into the dremel thing.  To their credit, at least the portions of the ramps in the barrel extension and the portions in the upper actually line up (it looks like they did it with the barrel & upper already mated).  That's better than Colt.  When I sent the 6520 back, they "fixed" it by dremelling some more to widen the ramps in the upper so that they now overlap the ramps in the barrel extension.  I bought the 6520 from CDNN for a nice price, but I guess you get what you pay for.

Nothing against either of these companies in general.  I think Colt is the gold standard (when they don't cut corners - and usually they don't - they gave me an RMA in a heartbeat and I was actually surprised they didn't give me a new done-right upper receiver instead of doubling down on the dremel).  I think CMMG is a solid mid-range AR vendor, and not their fault that my champagne tastes outgrew their Napa Valley offerings.  I probably should have bought a Colt or BCM A2 to start with.

Here are the CMMG dremelled feed ramps (in their own way more impressive than Colt's, but still breaking the anodizing).

       They're not all that bad from Colt. The first pick is a 6520
complete upper I sold a while ago. I kept another that looks the same,
and the unbarreled Colt upper receiver in the bottom pic is was also cut
before anodizing. All have 4 or M4 markings on the front of the carry
handle.







 
 



 

Yeh, yours look like what I was actually expecting when I ordered the Colt carbine from CDNN, and what I expected to get back from Colt after the warranty RMA.  I guess they had a bunch of A2 rifle uppers and no demand for A2 rifles so the decided to make 6520's out of them, and having no carbine barrels without M4 ramps decided to give the janitor a dremel.  Probably how that batch ended up at CDNN.

So, the CMMG dremel job on the A2 rifle is a lot more professional looking, but still means exposed soft white aluminum and hitting the ramps in the barrel extension is going to change the angle, so not what I'd prefer (hence this thread trying to get a line on a replacement A2 upper with ramps before anodizing).