AR180B-2 bolt head info

[H Wally]

Hi all,
yet another strange idea of mine - does anyone know if the AR180b-2 boltheads are similar in lug profile to those on the AR15? I'm not looking for component interchange, but rather whether or not an AR180 bolt head could be made to properly lock into an AR15 barrel.

Alternatively, if an AR15 bolt head would in fact fit, or could be made to fit into an AR180 bolt carrier. Really what I need is an AR15 barrel on an AR180.

Haven't found any info via google so had to ask

 

[cr5]

I think the lugs are the same but the bolt is not interchangeable (I think but not 100% sure) I was going to check that when I buy mine back from my buddy. I'm considering doing a 300BLK conversion on it if possible.
I should have it back sometime in July so I'll know then.

 

[Armedsask]

They are the same. An AR180B barrel extension is just a turned down AR15 extension and then press fit.

Buy an AR15 barrel with no extension and no gas port drilled. Slap it on, and drill the gas port. Be sure to read the FAQ on barrel removal.

 

[H Wally]

They are the same. An AR180B barrel extension is just a turned down AR15 extension and then press fit.

Buy an AR15 barrel with no extension and no gas port drilled. Slap it on, and drill the gas port. Be sure to read the FAQ on barrel removal.

Hmm - so the AR180 uses something like a barrel trunion like on an AK that the barrel fits into? How exactly does the AR180 bbl system work? I know the AR15 barrel system is held by what is in effect a large nut since the lugs themselves lock onto the barrel extension, however unsure what you mean by a turned down ar15 extension? The AR180 barrel fits to a receiver trunion, or there is in effect some kind of barrel extension on the 180 barrel?

 

[teenahlake]

The problem is the pin hole is 90degrees out of phase so wouldn't eject. The barrel trunnion is spot welded to the receiver, and then the barrel is screwed in. The trunnion is threaded to take AR15 standard

 

[H Wally]

Ahh - makes sense now. We're referring to the pin hole holding the barrel extension on? If so, why not just fit a new pin hole? I'm asking having never disassembled either rifle so I can't draw any inference on why this might not work.

 

[teenahlake]

No the bolt cam pin, if you could get an aAR 15 bolt before they drilled the cam pin you could probably drill for proper orientation the trunnion itself is press fit to the receiver. Then spot welded. A modified spline wrench can be used to remove the bbl. I will see if I can find a pic

 

[teenahlake]

 

[teenahlake]

Just Google image Are-180 bolt group you will see the difference wrt bolt cam pin

 

[H Wally]

No the bolt cam pin, if you could get an aAR 15 bolt before they drilled the cam pin you could probably drill for proper orientation the trunnion itself is press fit to the receiver. Then spot welded. A modified spline wrench can be used to remove the bbl. I will see if I can find a pic

Just Google image Are-180 bolt group you will see the difference wrt bolt cam pin

Ahhhk - I see where you're going - you're referring to the second part of my question regarding whether or not an AR15 bolt head could be made to fit a 180 carrier. That was mostly an idea if it turned out that 180 bolt heads were not the same profile as AR15 bolt heads.

In regards to the first part of my question, were I to somehow hog out the entire trunion on a 180b-2 to accept an AR15 barrel with barrel extension, I'm understanding that the profile of the 180's bolt head is such that the bolt would correctly lock into the AR15 barrel? I misunderstood you guys the first time. I understand that the 180's profile might be too small to fit an AR15 bolt extension, but for the sake of academic discussion I'm going to pretend there's room to mill out the AR180's press fit trunion to then insert an AR15 barrel with extension.

As it stands my idea is more along the lines of if I completely removed a barrel and barrel extension from the receiver and tried to fit a 180's bolt head to it to get it to correctly fit and headspace.

 

[jakester]

I had looked into this with mine. The AR 15 Extension has a shoulder on it which butts up against its Upper receiver. The barrel nut then tightens against the other side of the shoulder to keep the barrel tight. The AR 180b uses basically an AR 15 barrel extension, but with the Shoulder removed. (ie, straight shank) like an AK, but pressed into the uppers trunion. To remove the whole assembly, it needs to be pressed out. The barrel can be removed while leaving the extension in the trunion if you wish to go that route. It involves getting, or making an extension installation wrench (which has lugs which look like the bolts locking lugs attached to a handle). You clamp the barrel in a barrel vise, and insert the wrench into the extension from the bottom of the upper, and it basically unscrews the extension from the barrel, but because the extension is pressed into the upper receiver, it turns along with it. If you try to unscrew the barrel from the upper without using the extension wrench, the barrel and extension can turn in trunion and be out of alignment.

If memory serves, the gas port location on a 20" AR barrel is the same distance as on the AR 180b, however the shoulder where the sight base butts up to has a slightly different dimension. Nothing that couldn't be overcome though. So...you could turn off the shoulder on the AR 15's barrel extension, and press the whole barrel assembly into the the AR 180b's upper reciever. Before doing that, you would have to do whatever machine operations were necessary to fit the AR 180b sight base to the AR 15 barrel at the proper location.

I was going to try and find an old 20" Sp1 chrome lined barrel to do just that, but ended up selling the rifle instead.

 

[H Wally]

Ahh - that makes sense - I didn't really understand what Ardent had said not having seen how the AR180 looks internally. Thanks!

 

[cr5]

Ahh - that makes sense - I didn't really understand what Ardent had said not having seen how the AR180 looks internally. Thanks!

Where are you going with this?
Are you just planning to change the barrel for the sake of changing the barrel? I can't imagine you've got enough rounds down one to wear it out.
Are you thinking of trying to fit a match grade barrel into it? It will never be a sniper rifle so don't get your hopes up too high.
Keep in mind that by the time you pay for the barrel, machining and gunsmith work you could just sell the 180B and add in the money you will spend changing the barrel and buy a non restricted ACR.

I'm all for projects but I get the feeling this is going to be expensive for you since it sounds like you will be paying for all the work to be done.
Contact Ian at Herron Arms if you want more info, I'm sure he will be able to do the barrel swap for you and will use any quality barrel blank you wish to pay for.

 

[teenahlake]

You really couldn't mod the AR 15 bolt the cam pin is 90degrees from the AR180. The ejector/extractor points the wrong way the bcg has the eccentric cam, on the side AR180, vs AR15. Up top.......anybody with an AR180 please take pics of a BCG, and front of receiver with handguards off. Mine is 2000miles away

 

[foxbat]

Before anyone else tries 're-inventing the wheel', as per brother cr5, contact Ian Herron at Herron Arms.
I had him rebarrel my Ar180B to 6.5 Grendel so has the experience of those who have truly 'been there...done that'.

 

[H Wally]

Fair enough - I'm not actually trying to do anything to an AR180, but I find some threads get derailed if I post a lot of info and cloud the actual subject, plus my projects take so long I've taken some flak from people because they're looking for results. Since you guys are awesome and helped me understand how things work there's no risk at derailing now - looking for a straight pull take down bolt gun and looking at various donor designs for what would work best and how I could mix and match designs for the best end result on what I'm looking for. This project's anywhere from 6 months to 5 years off, but it'll take time for me to draw up plans and start putting parts together since I'm doing this in my very limited spare time

Where are you going with this?
Are you just planning to change the barrel for the sake of changing the barrel? I can't imagine you've got enough rounds down one to wear it out.
Are you thinking of trying to fit a match grade barrel into it? It will never be a sniper rifle so don't get your hopes up too high.
Keep in mind that by the time you pay for the barrel, machining and gunsmith work you could just sell the 180B and add in the money you will spend changing the barrel and buy a non restricted ACR.

I'm all for projects but I get the feeling this is going to be expensive for you since it sounds like you will be paying for all the work to be done.
Contact Ian at Herron Arms if you want more info, I'm sure he will be able to do the barrel swap for you and will use any quality barrel blank you wish to pay for.

You really couldn't mod the AR 15 bolt the cam pin is 90degrees from the AR180. The ejector/extractor points the wrong way the bcg has the eccentric cam, on the side AR180, vs AR15. Up top.......anybody with an AR180 please take pics of a BCG, and front of receiver with handguards off. Mine is 2000miles away