6mmbr ar 15 build

[RW]

Thinking of building a 6mmbr ar15. Is the only brass available the norma and lapua? Is there any cheaper brass available so if a person is shooting squirrels loosing brass wouldn't break you? Ron

 

[JLT]

A 6BR won't work on the AR-15 platform - the case head is too big. Not enough metal in the bolt for reliable function. You might want to look into the 6mm AR (based on the Grendel/PPC case - it's just a 6.5 Grendel necked down to 6mm) or the 6mm Hagar. Both of these are 'just small enough' at the case head to work in an AR-15.

If you're heart is set on a semi-auto AR in 6BR, you're going to have to go the AR-10 route. I would definitely go with the 6mm AR or the 6mm Hagar. You'll spend a lot less in the end, although I would highly recommend buying the absolute best bolt/bolt carrier available and get a spare bolt just in case something goes wrong at the worst possible time.

 

[zanemoseley]

I had a 6mm FatRat (6.5 Grendel necked down and shoulders blown out AI style), Lee Wells that invented it is a good guy to work with, he has Whidden dies for tje caliber. It shot good at 600 with Berger Hybrids.

Loaded cartridges were too long for the Alexander Arms 6.5 Grendel mags so I hand fed and filled the mag well with a bobsled. I could have worked up a mag length load but I was into f class at the time.

At the end of the day it felt a bit silly, it ended up being a single shot rifle that slung brass 6 feet. I sold it and put the money toward more practical stuff like my Savage 6br. If I really wanted a general purpose long range AR I would consider going with the AR/308 receiver size and chamber in 260 Remington. I would also be content with mag length loads, hand feeding an AR makes you just want a bolt rifle real quick.

 

[Spook]

I've built AR-15's (as in made the barrels and assembled) in 6BR ,6.5 and 30 BRX and 375 Whisper. PRI 6.8 waffle mags feed them pretty reliably.
Ive seen 15's fire wssm cartridges and that case has a .535 rim dia.

Brass catchers ?

 

[JLT]

I've built AR-15's (as in made the barrels and assembled) in 6BR ,6.5 and 30 BRX and 375 Whisper. PRI 6.8 waffle mags feed them pretty reliably.
Ive seen 15's fire wssm cartridges and that case has a .535 rim dia.

Brass catchers ?

Sorry - not possible from an engineering perspective.

 

[zanemoseley]

6.5 Grendel is the largest case I think I've seen on a modified AR15 bolt. You can see here how thin the web is between the lugs.

https://goo.gl/images/2v3Qe5

The base diameter on the 6.5 Grendel is .439 where the 6br is .473 so its roughly another 1/32". That would leave nearly nothing left in the webbing between lugs. While it may be physically possible I doubt it would last long at all.

 

[zanemoseley]

Here is a .30 RAR (Remington 30 AR) next to a .223 bolt, never heard of the 30 rar. Not strong looking at the least.

 

[ebb]

JLT yes it is, I shot with a guy that built one years ago.

 

[284driver]

Sorry - not possible from an engineering perspective.

Sorry, I have a 6brx sitting in the gun vault.

 

[RW]

It looks like the 6mmar would be the way to go as brass should be readily available and it looks very close to the 6br in performance was just looking for a accurate long range cartridge for an AR15 for maybe some 600 yard shooting that is versatile and something that I could put together,Ron

 

[JLT]

JLT yes it is, I shot with a guy that built one years ago.

Built what?

Sorry, I have a 6brx sitting in the gun vault.

Where did you get the bolt? I'm unaware of anyone currently making a .473 bolt head for an AR-15, .458 SOCOM notwithstanding, as it is a low pressure cartridge. It's been tried by several in the past and all have met a predictable end.

I've built hundreds and hundreds of AR-15s and AR-10s and I would never attempt to run anything bigger than a PPC base in an AR-15 platform. There's just not enough metal for reliability and safety. The supply side has figured that out, no doubt with a little urging from the plaintiffs' bar and/or the cost of warranty service.

I said it is not possible from an engineering perspective. Let me rephrase - It is absolutely irresponsible from an engineering perspective and the economics, taking everything into consideration, make it the equivalent of 'Here, hold my beer. Hey fellas, watch this!" I'll stand by that. If that were not the case, we'd all be running 6BRs and variants in our AR-15s. And we're not.

Further, the notion that WSSMs can function in an AR-15 is beyond preposterous. Get out your calipers and take a measurement or two. Remember, WSSMs and WSMs run at 64K psi. You first . . . .

 

[RW]

Built what?



Where did you get the bolt? I'm unaware of anyone currently making a .473 bolt head for an AR-15, .458 SOCOM notwithstanding, as it is a low pressure cartridge. It's been tried by several in the past and all have met a predictable end.

I've built hundreds and hundreds of AR-15s and AR-10s and I would never attempt to run anything bigger than a PPC base in an AR-15 platform. There's just not enough metal for reliability and safety. The supply side has figured that out, no doubt with a little urging from the plaintiffs' bar and/or the cost of warranty service.

I said it is not possible from an engineering perspective. Let me rephrase - It is absolutely irresponsible from an engineering perspective and the economics, taking everything into consideration, make it the equivalent of 'Here, hold my beer. Hey fellas, watch this!" I'll stand by that. If that were not the case, we'd all be running 6BRs and variants in our AR-15s. And we're not.

Further, the notion that WSSMs can function in an AR-15 is beyond preposterous. Get out your calipers and take a measurement or two. Remember, WSSMs and WSMs run at 64K psi. You first . . . .

Thank You, JLT I surely would want something that is reliable!! Ron

 

[JLT]

Thank You, JLT I surely would want something that is reliable!! Ron

RW, even with the best available bolt components, the PPC case head is close to the razor's edge. Make sure you get a spare bolt for the 6mm AR. I have a 6.5 Grendel AR that has seen about 5,000 rounds and I'm on my second bolt head.

A 6mm AR is an excellent choice if you want something with more legs than a 5.56/.223 out of an AR but you may want to wait just a little while until the .224 Valkyrie is formally introduced. Basically a 6.8 SPC necked to .224 and has the boiler room and case geometry to handle the 80 - 90 grain bullets at mag length.

 

[Ringostar]

Built what?



Where did you get the bolt? I'm unaware of anyone currently making a .473 bolt head for an AR-15, .458 SOCOM notwithstanding, as it is a low pressure cartridge. It's been tried by several in the past and all have met a predictable end.

I've built hundreds and hundreds of AR-15s and AR-10s and I would never attempt to run anything bigger than a PPC base in an AR-15 platform. There's just not enough metal for reliability and safety. The supply side has figured that out, no doubt with a little urging from the plaintiffs' bar and/or the cost of warranty service.

I said it is not possible from an engineering perspective. Let me rephrase - It is absolutely irresponsible from an engineering perspective and the economics, taking everything into consideration, make it the equivalent of 'Here, hold my beer. Hey fellas, watch this!" I'll stand by that. If that were not the case, we'd all be running 6BRs and variants in our AR-15s. And we're not.

Further, the notion that WSSMs can function in an AR-15 is beyond preposterous. Get out your calipers and take a measurement or two. Remember, WSSMs and WSMs run at 64K psi. You first . . . .

Olympic Arms offered Wssm AR's. An old friend that I grew up with was building AR's using the wssm bolt. He cut down 300 RUM cases to a straight walled 500. He had to remove the dust cover and mill out the ejection port. He named his round the 500XS. It used 50 cal pistol bullets.

 

[RW]

RW, even with the best available bolt components, the PPC case head is close to the razor's edge. Make sure you get a spare bolt for the 6mm AR. I have a 6.5 Grendel AR that has seen about 5,000 rounds and I'm on my second bolt head.

A 6mm AR is an excellent choice if you want something with more legs than a 5.56/.223 out of an AR but you may want to wait just a little while until the .224 Valkyrie is formally introduced. Basically a 6.8 SPC necked to .224 and has the boiler room and case geometry to handle the 80 - 90 grain bullets at mag length.

Before I do anything I am going to wait for the 224 Valkyrie to come out it sounds interesting to be able to shoot the heavy bullets with a little more steam!! Thank You, Ron

 

[JLT]

Olympic Arms offered Wssm AR's. An old friend that I grew up with was building AR's using the wssm bolt. He cut down 300 RUM cases to a straight walled 500. He had to remove the dust cover and mill out the ejection port. He named his round the 500XS. It used 50 cal pistol bullets.

Those are NOT AR-15 uppers. They just happen to fit an AR-15 lower pin spacing. Spring and buffer modifications are required as well. There is nothing milspec about it, therefore, it is not an AR-15. You can get a single shot .50 BMG 'upper' for a milspec AR-15 lower, but the rifle is not an AR-15 after you put that !#@*& thing on.

You can put a 440 Mopar in a Toyota Camry but, when you're finished, it ain't a Toyota anymore.

 

[JLT]

Before I do anything I am going to wait for the 224 Valkyrie to come out it sounds interesting to be able to shoot the heavy bullets with a little more steam!! Thank You, Ron

Good decision! I'm waiting on that one myself - should be interesting.

 

[ab_bentley]

Good decision! I'm waiting on that one myself - should be interesting.

The BR case can be adapted to the ar15 platform. Young Manufacturing developed a bolt capable of handling 60kpsi normal operating pressure. There's several people that have reliably built Dashers and BR variants on the AR15 platform. I built the equivalent to a 30br on a 15 platform after the jackass from the the 300 Reaper stole my money.
Adam

 

[Erud]

I had a 6mm BR AR about 6 or 7 years ago. It sucked. Got rid of it and got a 6mm AR Turbo 40° instead. Shot in excess of 10,000 rounds of that cartridge in competition with excellent results. Great round.

 

[Geno C]

Those are NOT AR-15 uppers. They just happen to fit an AR-15 lower pin spacing. Spring and buffer modifications are required as well. There is nothing milspec about it, therefore, it is not an AR-15. You can get a single shot .50 BMG 'upper' for a milspec AR-15 lower, but the rifle is not an AR-15 after you put that !#@*& thing on.

You can put a 440 Mopar in a Toyota Camry but, when you're finished, it ain't a Toyota anymore.

The DMV still considers that a Toyota...