AR operation question

[Karl-just-Karl]

First off, I understand most of the mechanics of what happens inside AR pattern rifles during firing, so I will skip the laborious details, unless someone wants to discuss it step-by-step.

My question is: What keeps the bolt extended out of the BCG during cycling when the bolt strips the next round from the magazine? To ask another way, what keeps the bolt from rotating over against the cam pin when the bolt is pushing the next round out of the magazine?

Just curious.

 

[Mgderf]

I don't believe there is room to the side of the bolt carrier to allow the bolt to cam over until just before it reaches the chamber.
You can not install a bolt into the upper if the bolt is retracted.

In short, the upper keeps the bolt from rotating. The cam pin has no place to go.

Edit

I just opened my safe and opened an AR.
I was right. There is a cut-out on the inside of the upper that allows room for the cam to turn just as the bolt face reaches the chamber.

 

[Sheepdog Gear]

I don't believe there is room to the side of the bolt carrier to allow the bolt to cam over until just before it reaches the chamber.
You can not install a bolt into the upper if the bolt is retracted.

In short, the upper keeps the bolt from rotating. The cam pin has no place to go.

Edit

I just opened my safe and opened an AR.
I was right. There is a cut-out on the inside of the upper that allows room for the cam to turn just as the bolt face reaches the chamber.

 

[Karl-just-Karl]

Yes, you are correct! Sorry, I don't have any prizes.

It hadn't dawned on me that the slot in the top of the receiver keeps the pin in place.

+1 for my laziness. The internet (and message board users) provides the solution again.

Thanks!


There is just something bout Stoner's design that amazes the heck out of me.

 

[rvb]

I don't believe there is room to the side of the bolt carrier to allow the bolt to cam over until just before it reaches the chamber.
You can not install a bolt into the upper if the bolt is retracted.

In short, the upper keeps the bolt from rotating. The cam pin has no place to go.

Edit

I just opened my safe and opened an AR.
I was right. There is a cut-out on the inside of the upper that allows room for the cam to turn just as the bolt face reaches the chamber.

Yes. It's also why that rear corner of that cutout sees wear which tends to freak out the newbs.
-rvb

 

[Mgderf]

There is just something bout Stoner's design that amazes the heck out of me.

I've heard it said that there is a fine line between genius and insanity.

It is my considered opinion that Mr. Stoner crossed back and forth over that line more than a few times while he designed that rifle.
So many individual components that are so simplistic in design, yet so complicated in their function.
Tie everything together and it's amazing what he came up with.

The AR platform is the grown mans erector set.

 

[cop car]

What Browning did, now that was insanely genius. The fact that he figured out all his designs, and so many designs is absolutely incredible. Especially with the state of the gun art when he came up with his ideas.