223/5.56 ammo opinions needed

[ST911]

From an April, 2012 handling session with a Windham, dry handling only and a field strip. Serial number was WW prefixed, number ~14000.

UPPER

Barrel stamped 5.56, 1/9.
Chrome lined.
Front sight base marked only with a crown.
Front sling swivel attached with a rivet.
Barrel profile had an M4 type stepdown, overall profile was about the same.
Dual heat shields, one black and one silver, both much closer together than GI. Pretty much laying on each other.
Carbine gas. Unknown port dim.
Railed upper, no addressing.
Keyhole forge mark.
Diamondhead BUIS.
Charging handle, typical BM. Felt tinny.
Auto carrier. Unmarked.
Carrier key was well staked, as in MOACKS quality staking.
Unmarked bolt.
Extractor spring insert black, w/ factory supplied o-ring.
Extended feedramps machined pre-anodizing, even alignment.

LOWER

Lower receiver keyhole forge mark, R side behind trigger guard.
GI type trigger group. Round hammer. Clean break.
Aluminum trigger guard.
GI grip, attached via allen head bolt.
Extruded receiver extension, appeared commercial dim.
Buttstock plastic light and cheap.
Extension and stock had angle-cut rear.
Carbine buffer, no birdshot. Felt about right, with normal range of motion internally.
Receiver extension nut unstaked. Tried to remove with hand tension and could not. No sign of thread locker.

Gun was sold in a BM like plastic case. Included a rudimentary manual, magazine, and promo lit for Windham Weaponry with pics and bios of the employees.

Pretty typical BM, with the exception of the well staked carrier key.

I have seen several others like this since. A couple passed Ned's 5.56 chamber gauge, but I didn't do them all.

[Tamara]

Bad ammo I assume?

Hard to say. Given the headstamp, it's unlikely to be the 5.56/.223 thing, so that makes my next suspicion a bum reload.

Cletus swore up and down it was factory ammo, but what're you gonna do?