Bolt lugs don't line up with feed ramps

[Griff79]

Guys,

I was shooting today, expended about 34 rounds and on the 35th round my bolt has become locked in the closed position. When you look down the bottom of the upper you can see that the bolt lugs are rotated about 1/8-1/4 thus not allowing the bolt to be drawn back.

There is not a round in the chamber, nor a spent casing or primer stuck. It became jammed earlier and I did get it to cycle by hand about 4-5 times then it became stuck again.

What has happened? Is this a quality control issue from the factory? Ideas?



Griff

[Jamnanc]

The last time this happened to me it was gas tube misalignment/mushrooming that caused it. I thought it was the ramps, but someone much smarter than me showed me the problem.

[BPTactical]

Debris between the cam pin and bolt carrier is a possible cause, tap the carrier rearward and it should unlock.

[Alpha2]

Too many moving parts. WAY to many moving parts!

[Danimal]

Deleted

[Circuits]

If you're that far forward, the cam pin has started to do its magic.... take a picture 1/2" further back when the bolt face first enters the barrel extension. Then we'll talk.

At that point in the bolt/carrier travel, the bolt lugs are SUPPOSED to be out of alignment because they're rotating to the locked position.

If you're trying to pull back from battery, it's because you're not pulling hard enough, but if that's as far back as you can pull the bolt carrier, then your cam pin is broken or something similarly bad.

[SideShow Bob]

I was shooting today, expended about 34 rounds and on the 35th round It became jammed earlier and I did get it to cycle by hand

That should have been the time to pull your BCG to inspect the parts for problems, or debris.
Continuing to fiddle about could have caused a minor problem to turn into a serious one.