Need opinion from resident gunsmiths / know it all's on this AR-15 chambering issue....

[USMC88-93]

Extractor / ejector hanging things up?

https://www.youtube.com/watch?v=kCBsVdtilP0

kCBsVdtilP0

Colt AR-15 Match HBAR (Ban era former Texas law enforcement agency weapon) that sucked down anything I fed it for years.
Colts semi auto half circle bolt carrier (less mass due to the neutering Colt used to do)
Not magazine related as this is repeatable with multiple magazines.
Does not appear to be a buffer spring loosing its punch as the bolt clearly goes into battery easily most of the time.
Nosler 77gr Factory loaded Custom competition ammunition.

I will be trying a different bolt, (but have to use the same carrier due to the Colt sear block) and a different lower with the same upper when I get the chance.

[USMC88-93]

..

[bryjcom]

Change the bolt or swap it with another rifle and see if that helps.

I had a sticky bolt that would close but had a hell of a time opening back up with the charging handle. That bolt just didn't like that barrel extension. Swapped the bolt and and no more problems.

[Brian]

Hmm, need more info. New gun, old gun with new problems??

Maybe polish feed ramps - are they m4 feed ramps on both sides?
Factory ammo? 5.56 or .223?
Match barrel / .223 wylde?
Tried swapping the bolt? Mag?

[earplug]

Bent gas tube, tweaked gas key. Take the BC apart and see if the bolt carrier slides freely on and off the gas tube.

[ray1970]

Personally, I would check the flux capacitor.
[Coffee]

[USMC88-93]

Bent gas tube, tweaked gas key. Take the BC apart and see if the bolt carrier slides freely on and off the gas tube.

https://www.youtube.com/watch?v=Ozixmrp5T1I

Ozixmrp5T1I

[BPTactical]

Extractor bent?
Clean under extractor and replace spring/buffer.
Clean ejector recess, spring and ejector.
Check cam pin for wear.
Check bolt carrier slot for wear.
Check upper for wear.
Adequate lubrication?
Burred barrel extension/bolt lugs.
Clean barrel extension.
Dirty buffer tube.
Worn buffer tube.

If the spring is closing the bolt that far, spring is likely good. Check free length to be sure.

[ar15shooter]

Will it chamber a factory 55 grain round?

[USMC88-93]

Will it chamber a factory 55 grain round?

It had for years prior to this, I will also be trying alternate ammunition when I have the opportunity but the chances of the ammunition being the cause at this point are slim.

[Gunsmith45B]

When is the last time you shot the firearm? How much force does it take you to push the bolt closed in your first video?
If you have shot it a lot the buffer spring may be worn down.

If you bring it by Ark Tactical I can take a look at it for you. I did small arms repair in the Army.