Ok, here's an interesting issue.

3 Colt flat top uppers
1 Colt A2 carry handle upper
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3 Colt milspec charging handles
2 Geissele Super Charging Handles
1 Geissele Airborne Charging Handle
ooooo

All the milspec charging handles fit all the uppers.
All the "G" charging handles fit all the flat top uppers.
None of the "G" charging handles fit the A2 upper.

I'm not seeing any binding or blockage inside the receiver. The latch just doesn't quite make it over the "hump" when pushed all the way in and won't lock in place. I only noticed because I had the A2 upper without a BCG in it and was wondering why the CH wouldn't stay locked in place.

Anyone else experienced such an issue?

Just tried a couple of Radian Raptor CHs and they fit the A2 upper without a problem.

How odd (for the "G"s).

Tight enough they won't come out if forced, or just need more lube and some break-in?

The CH is hitting the back of the receiver there's no way to force it.

I'll get a pic.

Here's a pic of it hitting the right (starboard) side of the receiver.



Here's a pic of the Raptor which "just" barely fits.

Some additional notes. The "G" perfectly fits the radius of the flat top upper.

I have another Colt A2 upper. It has the same off-center fitment issue, but the "G" CHs are able to lock in place on that one.

I'll just chalk it up to the Colt A2 upper being .

The radius on the upper is referenced off the sides.  On the flat top the center of the two sides are tightly controlled as that governs the centering of the Picatinny rails.

On the A1/A2 upper the sides are "as forged" so their location is not as tightly controlled, but the radius is still referenced off the sides.  You can see in the images the the radius on the A2 upper is off-center and interfering with the charging handle.

The radius on the upper is .375" and the radius on the charging handle is .437", and set far enough back so the tolerance on the upper radius does not interfere.  Perhaps the CH manufacturer should set the CH radius back a few hundredth of an inch.

By the way, the distance should be not less than 0.77" and the radius should not be less than 0.427

Thanks. That's very informative and helpful.