AR 308 issue

[Hunt5BN]

I just put together an AR 308. Aero Precision upper and lower, JP Bolt, Bolt carrier, barrel and captured recoil spring.

My question is, when the rifle is empty and the bolt is in battery there is about an 1/8 of an inch movement in the bolt carrier group. You can see the bolt carrier move forward and backward about an 1/8 of an inch when you raise the barrel up and down.

The rifle seems to function, but I am not sure how to fix this.

Thanks in advance!

 

[waveslayer]

The big issue with AR10's are the fact that there are no standard sizes, they are all different. It's nothing like an AR 15 at all when it comes to standard sizes, there are rare occasions but most AR's are plug and play parts.

Have you tried an Aero Precision Bolt and recoil spring. Most likely your rear buffer tub is not screwed in enough, thus there is play because the Captured Recoil Spring isn't all the way forward as it should be. Or the Recoil spring is too short, thus allowing the play you are seeing... Have you tried a standard buffer spring and buffer to see if it removes the play in the BCG?

Is your buffer tube all the way screwed in to ensure the BCG is resting against the Silent Capture Spring?

 

[budlight]

Hard to follow you. Are you saying that your buffer weight is not pushing the bolt forward at all times?

 

[waveslayer]

Hard to follow you. Are you saying that your buffer weight is not pushing the bolt forward at all times?

the buffer spring is not sitting flush with the BCG, so the BCG has some play.

 

[Darryle]

Sounds like he has normal operation. Since the key cannot abruptly turn 90º to unlock, it has to gradually rotate out of battery, what you are seeing is normal movement of the bolt carrier to begin the bolt unlocking.

To fully understand what I am describing, remove the bolt carrier group and play with the bolt and carrier, pushing and pulling on the bolt while firmly holding the carrier in place, you will see the interaction of the key, bolt and carrier.

 

[waveslayer]

Sounds like he has normal operation. Since the key cannot abruptly turn 90º to unlock, it has to gradually rotate out of battery, what you are seeing is normal movement of the bolt carrier to begin the bolt unlocking.

To fully understand what I am describing, remove the bolt carrier group and play with the bolt and carrier, pushing and pulling on the bolt while firmly holding the carrier in place, you will see the interaction of the key, bolt and carrier.

there should be no play with a securely locked up bolt on any AR. The buffer forces it into battery and the lugs turn to lock, LOCK, into place. There is no play at all with the bolt when you move the gun up and down etc.

Can you imagine if your Bolt action did this?... NO WAY

 

[Hunt5BN]

Thanks all! One more rotation of the buffer tube fixed the problem. Thank you for all the quick replies and great info!!!

 

[DirectDrive]

Thanks all! One more rotation of the buffer tube fixed the problem. Thank you for all the quick replies and great info!!!

You know you're in the right spot when the buffer tube is on the shoulder of the detent (keeper) without jamming it.

Check your buffer detent (keeper) for damage.
The detent and buffer should never make contact except when the rifle is shotgunned open for cleaning or disassembly.

 

[FireFlyFishing]

Thanks all! One more rotation of the buffer tube fixed the problem. Thank you for all the quick replies and great info!!!

Got to love an easy fix!

 

[Darryle]

The bolt is in battery, the bolt carrier is moving, not the bolt, reread his original post.

there should be no play with a securely locked up bolt on any AR. The buffer forces it into battery and the lugs turn to lock, LOCK, into place. There is no play at all with the bolt when you move the gun up and down etc.

My question is, when the rifle is empty and the bolt is in battery there is about an 1/8 of an inch movement in the bolt carrier group.

 

[waveslayer]

The bolt is in battery, the bolt carrier is moving, not the bolt, reread his original post.

Thanks, reread what the issue was stated in the first response. The problem was resolved. And no it's not totally in battery if there's any movement at all...

 

[ARlife4me]

What type of buffer tube is it (rifle, a5, carbine)? I know you stated it is fixed, but trying to fix the next issue before it starts.

Rifle tube (a1, a2) requires it to be screwed all the way in

A5, carbine needs to clocked (adjustment holes/boss) at 6o'clock w/the tube against the buffer retainer (still so the retainer will move down as to insert spring and buffer) as to keep it in place.

This will keep the necessary tension on the bcg as not to have the slack/play you encountered. This is easily to be know it is correct when closing the upper as the bcg will slightly push back/make contact on the buffer.

 

[joelpend]

No need to use a buffer detent and spring with a JP Silent Captured Spring.

 

[WYO300RUM]

Hunt5BN,
I tried to start a conversation with you/PM but is says I can't with you... ??? Looks like you have posted enough to be able to. Whatever. Who knows. It wasn't about your AR. It was about 5BN