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5/29/2006 8:43:01 PM EDT
I have a bushmaster old upper 11.5" barrel with fixed 5" flash hider
lower is a vltor carbine stock.

I load a magazine insert it and chamber a round and fire, the fired round gets extracted and thats it.

I put the upper on a different lower with a different bolt and carrier and the upper runs fine

I then swap back the original bolt and carrier on the new lower and it doesnt run.. it double feeds and then fires the chamber round, extracts the spent casing bbut again wont chamber a new round.

I dont know whats the problem ??
5/29/2006 9:03:56 PM EDT
[#1]
Magazine problem.

Have you tried using different mags?
5/29/2006 9:54:50 PM EDT
[#2]
yes , different mags, some brand new.
5/29/2006 9:59:02 PM EDT
[#3]
Is the BCG that works an m16 carrier?

Same weight buffer in both lowers?
5/29/2006 10:03:02 PM EDT
[#4]
yes

no. the carbine lower has a h buffer and the other lower was a a2 stock with standard buffer
5/29/2006 10:05:28 PM EDT
[#5]

Quoted:
yes

no. the carbine lower has a h buffer and the other lower was a a2 stock with standard buffer



So the m16 BCG works with the standard buffer, and any other configuration doesn't work?

Sounds to me like you're short stroking.  Try changing your buffer on the lower that doesn't work, and if needed go with the same carrier in both.

5/30/2006 8:09:00 AM EDT
[#6]
Using everything on the commando rifle as it was when having a problem, swap out only the carrier alone (use the commando bolt).

If this solves the problem, check the Allen bolts on the commando carrier key.  Chances are they are loose, and causing a gas leak.


5/30/2006 9:08:04 AM EDT
[#7]
one Allen bolt is loose, But how do I tighten it ?
5/30/2006 11:50:41 AM EDT
[#8]
Tighten the allen bolts to 35-37 in lbs (if you do not have a torque wrench, this is about the force needed to start to bend a small L type allen wrench).

Also, if the bolts are in question, it's best to just replace the both instead of them snapping off or stretching if they have been over torque from the start.

Once tighten, you will stake the key metal/surface to flow it’s metal into the nuts side spines (the key should already be staked, so you will just need to restake in the same spot on the key).
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