AR bolt lugs stay locked if no gas system present, correct?

[arakboss]

The action spring will keep the bolt locked in battery if no gas or manual cycling makes it do otherwise.

I won't have an action spring or an extension tube attached. I want to access the firing pin through center rear of bolt carrier. I still believe the lugs will stay locked until I pull on charging handle.

 

[asiparks]

Ummmm yeah... the gas system is also designed to provide enough energy to overcome the weight of the buffer and the power of the spring, so the lack of gas won't cycle the action, but there is still rearward force against the bolt from the cartridge itself...As the bolt tries to move backward, the cam will move in it's channel to rotate and unlock the bolt...I wouldn't be confident in the bolt staying locked without the addition force from buffer tube spring pushing it forward
.

 

[arakboss]

Ummmm yeah... the gas system is also designed to provide enough energy to overcome the weight of the buffer and the power of the spring, so the lack of gas won't cycle the action, but there is still rearward force against the bolt from the cartridge itself...As the bolt tries to move backward, the cam will move in it's channel to rotate and unlock the bolt...I wouldn't be confident in the bolt staying locked without the addition force from buffer tube spring pushing it forward
.

You are the first to suggest this (i think).
How far rearward do you think the bolt could move? How much force does a carbine spring apply to bolt carrier on closed bolt?

 

[asiparks]

I cannot say for I have not the balls to try your experiment....

 

[titsonritz]

You are the first to suggest this (i think).
How far rearward do you think the bolt could move? How much force does a carbine spring apply to bolt carrier on closed bolt?

He is 100% correct, the amount of movement will be dependent upon the load. Something needs hold it in place or it will move, whether or not that makes a difference as you intent to manual cycle the action is a big "you got me".

 

[titsonritz]

I didn't read the whole thread so sorry if it had been mentioned but how do you plan to strike the firing pin?

 

[arakboss]

I cannot say for I have not the balls to try your experiment....

I will make sure to keep the rear of the upper pointed away from the family jewels and use a mallet instead of my hand to smack the firing pin. After the first firing I will inspect bcg for rearward movement.

 

[arakboss]

I didn't read the whole thread so sorry if it had been mentioned but how do you plan to strike the firing pin?

The plan was to stick a bolt or rod through the center of the bcg and smack it. I may put a very short light spring on the rear of the firing pin to keep it from hitting the primer until I smack it good.

 

[titsonritz]

The plan was to stick a bolt or rod through the center of the bcg and smack it. I may put a light spring on the rear of the firing pin to keep it from hitting the primer until I smack it good.

So an AR zip gun.

I'd would think a rod that engages the rear of the BCG with a smaller spring loaded rod inside to strike the firing pin would do the trick.

 

[arakboss]

So an AR zip gun.

I'd would think a rod that engages the rear of the BCG with a smaller spring loaded rod inside to strike the firing pin would do the trick.

That sounds like a better solution. For this trip I want to keep it simple and test out whether the bcg is going to stay in place and see if I will be able to hit anything. I imagine aiming from the hip won't be producing sub moa results

 

[barrigadaharley]

Ive wondered about this as well....i recently bought a 450 bushmaster complete upper from Bear Creek and noticed that they are also selling Complete 450 Bushmaster uppers WITHOUT any gas system...Site mentions the uppers are tailored for areas where semi auto isnt allowed...hhuummm

Search results for: 'bca ar 15 complete bolt action upper assembly 16 4150 parkerized heavy barrel 450 bushmaster no gas block 1 24 twist w 15 mlok rail'

Bear Creek Arsenal manufactures the largest selection of affordable quality AR-15 and AR-10 Firearms, Uppers, Lowers, Barrels, Assemblies, and more!

www.bearcreekarsenal.com

 

[Unka-Boo]

Eons ago, right after the '94awb sunset, I built a pistol to run a .22 kit in. Used a chopped A1 barrel ( was like 5-6" long), rifle buffer with a peice of foam over it ( ace stock cheek foam iirc), flat top upper and a cheapy free float tube...ran great. Then I thought "wonder if I can still shoot 556"...Yup!
The looks were funny as the fireball was HUGE.

 

[joken]

back in the UK, we call them "straight pull" rifles

We have a neighbor in AZ that's a Limey and I can't understand half of what he says either.

 

[Member 34319]

Ummmm yeah... the gas system is also designed to provide enough energy to overcome the weight of the buffer and the power of the spring, so the lack of gas won't cycle the action, but there is still rearward force against the bolt from the cartridge itself...As the bolt tries to move backward, the cam will move in it's channel to rotate and unlock the bolt...I wouldn't be confident in the bolt staying locked without the addition force from buffer tube spring pushing it forward
.

Then why don't bolt action bolts fly rearward?

The lugs are square. The lugs on the barrel extension are square. How would the bolt rotate without the carrier movement?

I've witnessed first hand a person putting a bolt into a barrel extension and putting a firing pin in. Whacked it with a hammer and it went bang. Bolt didn't go anywhere. No carrier attached, but I'm certain it wouldn't of mattered if there was or if the barrel was attached to an upper.

 

[Ramjet57]

So there is an error in this discussion in that the gas from the barrel enters the bolt carrier and the pressure pushes the bolt carrier away from the bolt the bolt then rotates and unlocks, the remaining chamber pressure then pushes the bolt and carrier rearward. With no unlocking the bolt won't move.

 

[Brian Vedack]

Then why don't bolt action bolts fly rearward?

The lugs are square. The lugs on the barrel extension are square. How would the bolt rotate without the carrier movement?

I've witnessed first hand a person putting a bolt into a barrel extension and putting a firing pin in. Whacked it with a hammer and it went bang. Bolt didn't go anywhere. No carrier attached, but I'm certain it wouldn't of mattered if there was or if the barrel was attached to an upper.

THANK YOU! I was about to say the same thing...the bolt does not cause any rotation. The movement of the carrier causes bolt rotation. Only on the cmmg rotary delayed blow back does the bolt cause rotation.

 

[Brian Vedack]

So there is an error in this discussion in that the gas from the barrel enters the bolt carrier and the pressure pushes the bolt carrier away from the bolt the bolt then rotates and unlocks, the remaining chamber pressure then pushes the bolt and carrier rearward. With no unlocking the bolt won't move.

Correct. The movement of the carrier causes the bolt to rotate either locking or unlocking. When in doubt. Google straight pull ar bolt action rifle. No gas system. No buffer spring. Nothing. Works like it should.

 

[asiparks]

Then why don't bolt action bolts fly rearward?

The lugs are square. The lugs on the barrel extension are square. How would the bolt rotate without the carrier movement?

I've witnessed first hand a person putting a bolt into a barrel extension and putting a firing pin in. Whacked it with a hammer and it went bang. Bolt didn't go anywhere. No carrier attached, but I'm certain it wouldn't of mattered if there was or if the barrel was attached to an upper.

a) I can't speak for all bolt actions, but on mine, and all those I've seen, after you push the bolt forward, you invariably push it down to lock it. Then you lift it up to unlock it, before pulling it rearwards.
b)The lugs are square. The lugs on the barrel extension are square. How would the carrier move back without the bolt rotating to unlock ?- If the lugs and bolts were all truly square then nothin g would move. Something you can try at home: Take out the rear pin on your AR and break it open. Now, point the muzzle at the ceiling. just the weight of the bolt is probably going to cause itself to unlock and drop rearwards until it catches on the CH.

Equal and opposite forces- as the bullet moves forward down the barrel and equal amount of force is pushing back against the bolt face. It how most of your 9mm ARs work: Blowback.

 

[asiparks]

We have a neighbor in AZ that's a Limey and I can't understand half of what he says either.

you think I type peculiar,, wait till you hear the words coming from me gob....

 

[Brian Vedack]

"How would the carrier move back without the bolt rotating to unlock"==the gas impingement system uses gas from the gas tube to force the carrier back, thus unlocking the bolt by use of the cam pin.

"Take out the rear pin on your AR and break it open. Now, point the muzzle at the ceiling. just the weight of the bolt is probably going to cause itself to unlock and drop rearwards until it catches on the CH."==the weight of the carrier will unlock the bolt and it will fall out. Put just the bolt in, lock it up, and I bet it won't move.
Thing to remember about ARs...there is a 'bolt' and a 'carrier'. Together they are not called 'the bolt'. Together they are called the 'bolt carrier group' or BCG. Without the carrier the bolt won't rotate either way.
As for bolt action rifles locking... that is to prevent out-of-battery detonation and to properly align the trigger group for proper operation.