.204 Ruger Upper

[Robbartley]

I tried two different. 223 BCGs. Same result.

 

[crapshoot]

It is. But if the one they sent you is "locking up" on an empty chamber, try a different one to see if there is any change.

 

[crapshoot]

Inspect the barrel extension for burs & debris. Also make sure your gas tube isn't binding in the gas key.
If nothing is evident then it is possible someone botched putting the barrel extension on the barrel and its out of spec. Possible but unlikely. In which case you'd have to contact the barrel manufacturer.
Just thinking out loud here. I'm by no means an AR technician.

 

[Kwarw1]

Are you using reloads for this test? Are you letting the bolt slam closed or just pushing with your finger?
I would take it out side, pointed in a safe direction and let it slam closed on a factory round a couple of times and see what happens with a known good bolt.
If that is a no go I would remove the gas tube just to remove that from the equation.

 

[Don_P]

If it locks up on an empty chamber it's time to strip the bolt and check the fit with headspace gauges.

 

[spotstalkshoot]

When assembly AR's, I check the bolt/ extension fit before upper and barrel go together. Check the gas tube alignment, check that the firing pin/key is installed properly and and everything is lubed that needs lubing. Also before pulling upper apart, remove the aftermarket trigger and cycle bolt to see if it opens correctly.

 

[popper43]

"BCG locks up without anything in the chamber" By locks up you mean hard to open the bolt? You did lube everything to really 'wet'? Probably extension assembled wrong.

 

[Robbartley]

So I cleaned the chamber, removed firing pin and bolt, cleaning and lubing wet. The BCG goes into battery with an empty chamber but fails to go into battery with a brand new casing, reload, and a factory load. BCG cycles manually, returning to battery. I will order a Go Gauge as the next step.