Chambering an AR barrel

[kfreeze]

thanks for the lead on the 7mm Valkyrie guy. I didn't see bolts and barrel extensions available but I will email him and ask.
I also have some of the modified PRI mags with the front cutout to allow longer length.

He said he would sell me bolts and barrel extensions a few years ago. They use stuff for higher pressures

 

[bamban]

thanks for the lead on the 7mm Valkyrie guy. I didn't see bolts and barrel extensions available but I will email him and ask.
I also have some of the modified PRI mags with the front cutout to allow longer length.

Try these guys. We bought BE from them.

Triune Precision

AR-15 and AR-10 Barrel Extensions made to match grade quality

triuneprecision.com

 

[ARlife4me]

Try these guys. We bought BE from them.

Triune Precision

AR-15 and AR-10 Barrel Extensions made to match grade quality

triuneprecision.com

Would they offer an extension for single feed? So, those extensions are bases on cartridges? With short mag cartridges the cartridge sits in the middle like single stacks and would benefit more of that design.

I' decided to check the extensions on my AR10's chambered in 6.5prc (McGowen) and 7saum (X-Caliber). The 6.5 has duel feed ramps and the 7saum has single feed. I guess I'll find out if 1 or both operate as designed?


@Mike D Texas you could get custom chambered? Also about the re-chambering of what you do have could pose a problem with headspacing? From what I've seen on how it's done the gas port is reamed after the extension and headspacing is finished as to correctly dial in the port. This keeps port at 12 o'clock with the index pin on extension and feed ramps at 6 (respectively).

 

[bamban]

Would they offer an extension for single feed? So, those extensions are bases on cartridges? With short mag cartridges the cartridge sits in the middle like single stacks and would benefit more of that design.

I' decided to check the extensions on my AR10's chambered in 6.5prc (McGowen) and 7saum (X-Caliber). The 6.5 has duel feed ramps and the 7saum has single feed. I guess I'll find out if 1 or both operate as designed?


@Mike D Texas you could get custom chambered? Also about the re-chambering of what you do have could pose a problem with headspacing? From what I've seen on how it's done the gas port is reamed after the extension and headspacing is finished as to correctly dial in the port. This keeps port at 12 o'clock with the index pin on extension and feed ramps at 6 (respectively).

I don't know what else they offer. Here are a couple I bought from them to mitigate VLDs from getting caught in the BE so called feed ramp. These will also aid better feeding with fat bullets.

 

[ARlife4me]

I don't know what else they offer. Here are a couple I bought from them to mitigate VLDs from getting caught in the BE so called feed ramp. These will also aid better feeding with fat bullets.

View attachment 519315

That's what the BE looks like on the 7saum. I've never paid any attention to the various ramps on the wide range of cartridges I have in 15' and 10's. Are they more about the bullets or the case/brass feeding than bullets?

 

[bamban]

That's what the BE looks like on the 7saum. I've never paid any attention to the various ramps on the wide range of cartridges I have in 15' and 10's. Are they more about the bullets or the case/brass feeding than bullets?

Mags

 

[Mike D Texas]

Would they offer an extension for single feed? So, those extensions are bases on cartridges? With short mag cartridges the cartridge sits in the middle like single stacks and would benefit more of that design.

I' decided to check the extensions on my AR10's chambered in 6.5prc (McGowen) and 7saum (X-Caliber). The 6.5 has duel feed ramps and the 7saum has single feed. I guess I'll find out if 1 or both operate as designed?


@Mike D Texas you could get custom chambered? Also about the re-chambering of what you do have could pose a problem with headspacing? From what I've seen on how it's done the gas port is reamed after the extension and headspacing is finished as to correctly dial in the port. This keeps port at 12 o'clock with the index pin on extension and feed ramps at 6 (respectively).

This is already a fully chambered and assembled 6ARC barrel. Everything is already indexed. The diameter and length to shoulder datum are smaller on the 6ARC than the Dasher. All I plan to do is ream this chamber out to 6 Dasher.

 

[Varmiter71]

I am very interested as well.
Someday I plan on doing a 22 dasher on an ar-15 using Olympic arms barrel extension/nut, bolt, and umar mag,

 

[ARlife4me]

This is already a fully chambered and assembled 6ARC barrel. Everything is already indexed. The diameter and length to shoulder datum are smaller on the 6ARC than the Dasher. All I plan to do is ream this chamber out to 6 Dasher.

But still would need to be headspaced. If you remove the extension you might not get it back to the correct location which could change based on how the chambering is done (to deep or to shallow) will change headspace. I guess reaming a little at a time as not to be out of go/no-go specs. This is beyond my field and only going thru what ifs.

 

[bamban]

But still would need to be headspaced. If you remove the extension you might not get it back to the correct location which could change based on how the chambering is done (to deep or to shallow) will change headspace. I guess reaming a little at a time as not to be out of go/no-go specs. This is beyond my field and only going thru what ifs.

Assuming using the same BE, the easiest way to transfer headspace - insert ARC GO gauge(GG) in the chamber. With depth mic, measure from the back of the BE to the back of the GG.

When chambering to the Dasher just duplicate the number using the Dasher GG.

 

[TonyRumore]

6mm Dasher is going to blow the lugs off the .473" bolt at 52k psi. You're going to have to down-load it.
The more you neck down the case, the more bolt thrust you're going to have. American Firearms already did the 6BR in 1995 and blew the lugs off the bolts. The 7BR blew them off too.

I don't know how much pressure you can run, but it won't be 52k.

Generally speaking, the largest rim size the AR-15 can handle at 50k+, is .440" (7.62x39 size).

If you want more speed in your 6mm AR than the ARC, you just need a longer ARC. Like this one (center).
Left to right - 6ppc, 6ARC, 6Tromix, 6.5Grendel, 6.8SPC.

Tony Rumore
Tromix

 

[Varmiter71]

How do they do the Wssm line then

 

[TonyRumore]

How do they do the Wssm line then

It's a hybrid AR-15 using an AR-10 bolt. Same as the 30 Remington AR.

Tony

 

[Varmiter71]

Somewhere I have a bolt and barrel extension/nut from Olympic arms for their 22-250 that I want to do a 22 dasher some day