Chambering an AR barrel

[Mike D Texas]

I have a 6ARC AR15 barrel that I want to rechamber to 6 Dasher. I can use 6.8SPC mags and it appears that it will feed just fine.

My question is, since the barrel extension is already attached to the barrel, and the case diameter is larger on the Dasher, does the reamer just run through the barrel extension?

I tried finding a video of rechamber if an existing barrel but have been unable to find one.

 

[sierracharlie338]

I've never heard of this being done so I'm curious now as well. Always looking to learn something new.

 

[Bert01]

I would think as long as the dasher reamer OD is less than the ID of the extension you should be fine. I can check the OD of my dasher reamer, if it would help. I dont have a large barrel extension handy though.

 

[Mike D Texas]

I would think as long as the dasher reamer OD is less than the ID of the extension you should be fine. I can check the OD of my dasher reamer, if it would help. I dont have a large barrel extension handy though.

I know the ARC barrel extension is a smaller diameter than the Dasher cartridge case.the Dasher case will not pass through the barrel extension.

 

[Bert01]

If the barrel extension is a smaller diameter than the case you are trying to put through it then I don't think you can use it. Maybe I'm misunderstanding what your asking. I was assuming this was an AR-10 variant since you were trying to go to the Dasher. The dasher won't fit on any AR15 bolt that I'm aware of that uses a standard extension.

 

[Mike D Texas]

If the barrel extension is a smaller diameter than the case you are trying to put through it then I don't think you can use it. Maybe I'm misunderstanding what your asking. I was assuming this was an AR-10 variant since you were trying to go to the Dasher. The dasher won't fit on any AR15 bolt that I'm aware of that uses a standard extension.

You are correct in that it will not fit the particular extension that I have installed on this barrel. However they do make larger diameter AR15 extensions to serve cartridges like the 458 Socom, 450 Bushmaster and 50 Beowulf.

What I'm unsure of if whether the diameter is corrected with a different extension or if it's created by the appropriate reamer.

Since the headspace is created within the barrel extension my assumption was in order to have the correct diameter for the cartridge, that the opening would be enlarged with the appropriate reamer to properly fit the cartridge case diameter and cut the chamber.

I know the shoulder sets the headspace however my thinking is you don't want to use one of the other framers that would be grossly larger than the diameter of the Dasher case.

The Dasher has a ~.473 head diameter so a 458 Socom bolt will work.

 

[Bert01]

That's what I meant about standard extensions. The .458 setup uses a dedicated extension made for that bolt. I guess you could ream a standard one, but you would need to ream it to match the bolt lugs not necessarily the cartridge.

 

[Mike D Texas]

That's what I meant about standard extensions. The .458 setup uses a dedicated extension made for that bolt. I guess you could ream a standard one, but you would need to ream it to match the bolt lugs not necessarily the cartridge.

I'm not sure it's any different. The .458 bolt I have goes into the extension, turns and locks up.

 

[KRP]

I'm not sure it's any different. The .458 bolt I have goes into the extension, turns and locks up.

If the bolt goes through the extension, why won't the cartridge? No rebated rim on a Dasher so the largest diameter is the case head.

 

[LRhunter514]

Take the bbl extension off before chambering.

 

[Mike D Texas]

Take the bbl extension off before chambering.

So how do I address the under size diameter of the barrel extension.

I tried to remove the extension with no luck so far.

 

[LRhunter514]

The extensions are threaded on.

 

[Bert01]

You have to remove the pin first.

 

[Mike D Texas]

The extensions are threaded on.

I'm aware. I have the tools to remove it.