Could use opinion on what could be causing this...

[BPTactical]

I'm not intimately familiar with piston driven rifles, but I took it down and watched how the parts worked.

I removed the piston block, and stuck a dewey rod in the piston chamber. I pushed down and watched the BCG in the ejection port. I noted that the when the guide-rod spring was fully compressed, the BCG was only half-way open.

I then removed the guide rod spring and repeated my test. This time I could move the BCG all the way open via the piston rod.

So, I'm wondering if the guide rod is supposed to go all the way back OR the rod only opens it part way and the momentum opens it completely?

Checked the things you suggested and it looks good....

Given this info I would be questioning if there is an error in the assembly.
I am only shooting in the dark here Ray, I have only fiddled with an ACR once or twice and that was in a retail environment.
Anxious to take a look though.....

[AR_ART]

If I can't figure it out it just may be coming your way. I'm going to check with Bushmaster themselves first and if they are no help, you'll be hearing from me...

Given this info I would be questioning if there is an error in the assembly.
I am only shooting in the dark here Ray, I have only fiddled with an ACR once or twice and that was in a retail environment.
Anxious to take a look though.....

[BPTactical]

If I can't figure it out it just may be coming your way. I'm going to check with Bushmaster themselves first and if they are no help, you'll be hearing from me...

The welcome mat is out if ya need!

[AR_ART]

Thanks! Its still might come your way. It appears the extractor is not "releasing" or letting the case go. I cycled it manually and it did not fling the round out. I check the bolt and ejector earlier and while its very stiff it seemed to work.

What makes operates the ejector? What makes it release the case?

[ray1970]

What makes operates the ejector? What makes it release the case?

The case should stay under the extractor until the ejector kicks it out of there. Is the ejector a plunger type like on the AR platform?

[BPTactical]

I can't make an accurate statement, like I said I have just casually fingered one.
An AR for example uses a spring loaded plunger on the opposite side of the bolt from the extractor. It is compressed when the round is stripped from the magazine and held compressed until the spent case clears the chamber. It then uses the extractor as a fulcrum and rotates the casing clear of the action.
An AK uses a section of rail on the left side of the receiver as an ejector. The casing is again held by the extractor and after firing this section of rail rotates the casing clear as the bolt travels rearward.

[AR_ART]

Woot! Thanks for the explanation! I think I found what's wrong, check this out;



The ejector is either stuck down inside or its broken. I pushed on it with a punch and it moves so it feels like the spring is still there!

I can't make an accurate statement, like I said I have just casually fingered one.
An AR for example uses a spring loaded plunger on the opposite side of the bolt from the extractor. It is compressed when the round is stripped from the magazine and held compressed until the spent case clears the chamber. It then uses the extractor as a fulcrum and rotates the casing clear of the action.
An AK uses a section of rail on the left side of the receiver as an ejector. The casing is again held by the extractor and after firing this section of rail rotates the casing clear as the bolt travels rearward.

[ray1970]

Yep. Definitely doesn't look good. Should be an easy fix. You'll be back up and running in no time. My guess would be it takes a standard AR spring and plunger.

[AR_ART]

Thanks for everyone's help and suggestions in getting this figured out!

[BPTactical]

Might be a little tricky to get out, when you get it out check the ejector and its bore for any burrs and address them as needed.
Probably wedged a piece of brass or such, causing it to stick.