Bolt Goes Forward When Rifle Bumped

[Heidevolk]

I'm pretty new to understanding how an AR functions, but when the Stock is bumped mildly (such as just set down on the floor) the Bolt flies forward.

Is this a sign the lower/buffer tube has problems and should be fixed, or is this common?

[emt370]

Normal so long as you mean when the end of the butt hits and not the side. Your handgun will likely do the same thing with the slide locked back when you hit the frame. Simple inertia at work.

[kwrangln]

Check the following thread and the pics in it to make sure your bolt catch is installed properly. If it is, then it is normal for it to release when the rifle is banged around.

https://www.m4carbine.net/showthread.php?t=49171

[citizensoldier16]

I've got an M14 and a Garand that will do this when bumped against the ground. Also, my G17 chambers a round if you insert the magazine with enough force. It's just inertia. Nothing to be worried about, just maintain muzzle discipline at all times.

[ucrt]

.

Remember the guy that told the doctor, "It hurts when I press right here." and the doctor replied, "Well...don't press right there!"

Just don't bump it... :)

FWIW...both of mine close with just a minor bump to the kick pad.

.

[5pins]

Yes it is normal. It will also cost you pushups in basic.

[JSantoro]

Completely normal. It'd be unusual if your bolt didn't go forward if the stock is bumped from the long axis.

Bolt's held in place by the catch.

BCG's weight, upon impact at the butt, pushes on the buffer spring enough for it to move slightly rearward, and the catch drops due to the tension of its own spring.

As the BCG returns forward due to the push of the buffer spring, the catch is no longer in its former place to keep the BCG from going fully forward.

Impossible to count how many times at boot camp somebody went from Port Arms to Order Arms with an open bold (not supposed to!), and have the weapon rebound off the deck with a loud CLACK! as the bolt drives home. Usually with the following result:
http://img219.imageshack.us/img219/8923/60203022.jpg

(Also completely normal)

[M4Fundi]

Same thing with the FAL

[Ned Christiansen]

DPMS uses a bolt stop with a chamfer on top for some reason. It makes for a real "hair trigger", super easy to drop the bolt. No idea why they do this, I've changed a bunch at classes or just ground off the chamfer when I didn't have a spare bolt catch..... we just can't have bolts that drop when you give the gun a mean look.

Here's a pic..... also shows another pet peeve, FP retaining pins that don't have a chamfer all the way around. It's amazing what people will do to save $.0000000000003 per gun, no matter the consequences to the end user.
http://www.louderthanwords.us/mediumfoto/picts/ulfls/07112010/15715599011.jpg