6mm ARC

[dwinmeade]

A new name for an old cartridge...the 6mmAR has been around for over 10+ years. Now there's 6mmAR Turbo. Looks like Hornady might be 'borrowing' somebody else's concept and calling it their own. Shame, shame.

 

[Buck Fever]

If that was it, that's good.

Any time a wildcat graduates to factory ammo with properly head stamped brass, that's a good thing.

Since that's not the story, this is the fifth or sixth time someone has invented this wheel and each time they ignored the bolt issue.

There is now a big pile of very similar stuff that's all incompatible.

 

[Deleted member 103481]

When Alexander Arms developed it, they modified .223 bolts and deepened the bolt face which significantly reduced the cross section of metal supporting the bolt lugs. When you load 6.5 Grendle hot enough to stay supersonic at 1,000 yards with 123 grain bullets in a 20" or shorter barrel, the bolt lugs like to break off.

The SPC was essentially a clean sheet of paper design and they made sure their case head left enough meat in the bolt face. Sadly 6.8 SPC and 6.5 Grendle were compared a lot because they both hit the scene around the same time. They were designed for two entirely different purposes.

6.8 SPC isn't trying to be a 1,000 yard target round. 6.5 Grendle isn't trying to be a potential 5.56x45 replacement.

I've got a 6.8 SPC and it is great. It runs like a top and shoots sub-MOA out to 600 yards, I haven't tried farther.

I have 6.5 Creedmoor for 1,000 yard shooting because I don't want to deal with 6.5 Grendle issues and I'm glad to step up to 147 grain bullets and about 200fps more muzzle velocity.

I've got a TAC6 wildcat for when I want to shoot 1,000 yards with an AR15. It shoots a 105 grain Berger about 2,700fps from an 18" barrel.

I'm assuming this is why max psi is only 52k?

I still don't mind the idea of one since the only purpose I would have one for is 600 yard plinking and it seems like even loaded tamely it wouldbe better than 223 for wind calls. Then again I'm stillnot willing to jump in yet as I have way too much invested in reloading 223 and don't really want to add another cartridge.

I had not heard of grendels being such havok on bolts that makes me hesitate more than any other factor by far

 

[Johnslam]

I'm assuming this is why max psi is only 52k?

I still don't mind the idea of one since the only purpose I would have one for is 600 yard plinking and it seems like even loaded tamely it wouldbe better than 223 for wind calls. Then again I'm stillnot willing to jump in yet as I have way too much invested in reloading 223 and don't really want to add another cartridge.

I had not heard of grendels being such havok on bolts that makes me hesitate more than any other factor by far

I've had my Grendel for six years now. I've shot several hundred rounds a year with it and had zero issues.

 

[Buck Fever]

With box ammo or mild reloads, the Grendle bolt might last a while.

There have been plenty of Grendles that lost bolt lugs but most of them seem to be years ago before box ammo became common.

It's still marginal, thing have just been dialed back a bit.

I don't understand why anyone wants to take a chance with it. If you want to shoot long, get a 6.5 Creedmoor, if you want 1,000 yards in an AR there are options without bolt issues.

If you are shooting anything that pushes high pressure, get an ARP Super Bolt for insurance.

 

[coop2564]

Nothing in AR15 can produce a bullet to hold much more than 1000FLB passed 350yds and stay spec. I'll keep my 6.8 for hunting.

 

[CaptnC]

As for the AR bolt issues, I personally have had 5 - 10.5", 16" (didn't shoot with a can on it, but fine without) sold that upper, 18", 20" and 24".

IMO-it does better with lighter bullets...which follows what the 6mm on the AR-15 platform suggests.

I'm in the process of figuring out which 6.5mm, 100gr bullet to use for hunting. So I can get a bit more velocity and still have the accuracy I want. 90 to 110 grains seems to be a sweet spot for accuracy in a couple of my rifles.

I did an experiment with 120gr speer bullets...cut the lead tip off and hand drilled into the bullet to get the weight down 10 grains. I made a jig the swedge the tips down a little so it wouldn't have the big HP end.

Best shooting bullet I've used in three different AR's 10.5", 18" and 20" barrels.

But the 6mm bullets (heavy for caliber) will out perform the light weight 6.5mm bullets because of a better BC so I can see the advantage.

The 6.5mm 90gr TNT are sweet shooters but I wouldn't try one on a deer!

 

[KaSH0508]

I have been shooting a 6mmAR For years now it's a fun versatile round. I run 55s for PDs, 75 VMAXs for coyotes and 95 SMKs to 108 ELDs for long range steel plinking. I also have plenty of .223s, 6.8 SPCs and a 6.5 Grendel. The only downside to both the 6mmAR and the 6.5 Grendel is the brass and occasional the bolt. The brass bulges at the base of the case if pushed. I have tried every type of brass, Hornady has soft primer pockets, Lapua holds pockets but bulges at the base, Starline also bulges at the base, The only one that holds remotely is the Norma and it is stupid expensive. I just roll with the Hornady as it is cheap. I have also broken bolt lugs on 2 Grendel bolts in the past. I have never had an issue whatsoever with 6.8 brass or bolts it seems to hold up way longer and at a bit higher pressure. This is a good thing in my eyes though, a Wildcat going factory is great. Maybe slightly slower than what I been running due to the shoulder being pushed back reducing case capacity slightly. Not enough to make a huge difference though, maybe 20-30 FPS. Better components from more manufactures will follow.

 

[Axl]

When Alexander Arms developed it, they modified .223 bolts and deepened the bolt face which significantly reduced the cross section of metal supporting the bolt lugs. When you load 6.5 Grendle hot enough to stay supersonic at 1,000 yards with 123 grain bullets in a 20" or shorter barrel, the bolt lugs like to break off.

The SPC was essentially a clean sheet of paper design and they made sure their case head left enough meat in the bolt face. Sadly 6.8 SPC and 6.5 Grendle were compared a lot because they both hit the scene around the same time. They were designed for two entirely different purposes.

6.8 SPC isn't trying to be a 1,000 yard target round. 6.5 Grendle isn't trying to be a potential 5.56x45 replacement.

I've got a 6.8 SPC and it is great. It runs like a top and shoots sub-MOA out to 600 yards, I haven't tried farther.

I have 6.5 Creedmoor for 1,000 yard shooting because I don't want to deal with 6.5 Grendle issues and I'm glad to step up to 147 grain bullets and about 200fps more muzzle velocity.

I've got a TAC6 wildcat for when I want to shoot 1,000 yards with an AR15. It shoots a 105 grain Berger about 2,700fps from an 18" barrel.

Bill Alexander did NOT use modified .223 bolts, he used modified 7.62x39 bolts that Colt had developed. If you use an actual 6.5 Grendel bolt and don't run over pressure loads you will not break bolts.

http://www.65grendel.com/forum/showthread.php?7420-The-Story-of-the-Grendel-bolt

 

[Buck Fever]

I learned about Grendle bolts around 10 years ago so I didn't remember that one detail about 7.62x39 bolts.

The bolts still break, that's the important part.

You still see people get surprised when you mention it so obviously it's not as well known as it should be.

 

[CaptnC]

I learned about Grendle bolts around 10 years ago so I didn't remember that one detail about 7.62x39 bolts.

The bolts still break, that's the important part.

You still see people get surprised when you mention it so obviously it's not as well known as it should be.

Maybe they are surprised because it doesn't happen with any real frequency?

I've never had one break...

But I will say I try to stay within the recommended pressures (by monitoring velocity) for the platform. I have shot some hand loads that were not over pressure until I screwed my can on. So I do load right on the edge, but I use velocity to tell me if at I'm getting close to max pressure.

6.5 Grendel Hornady brass...I have 25 to 30 of the first cases (over 2 years ago) I got for Grendel's. Last loading I lost 5 cases so they are now loaded as hunting ammo so i dont have to worry about recovering brass.

I've had good brass life by staying within recommended max velocities. I have cases where it's getting hard to see the head stamp. Some of the letters are getting to read. But I will not shoot ammo that leaves ejector marks.

Yes I know some of Hornady's own factory loading are hot. I see the cases when I'm picking up range brass and a buddy who doesn't reload gives me his brass.

 

[Axl]

Maybe they are surprised because it doesn't happen with any real frequency?

I've never had one break...

But I will say I try to stay within the recommended pressures (by monitoring velocity) for the platform. I have shot some hand loads that were not over pressure until I screwed my can on. So I do load right on the edge, but I use velocity to tell me if at I'm getting close to max pressure.

6.5 Grendel Hornady brass...I have 25 to 30 of the first cases (over 2 years ago) I got for Grendel's. Last loading I lost 5 cases so they are now loaded as hunting ammo so i dont have to worry about recovering brass.

I've had good brass life by staying within recommended max velocities. I have cases where it's getting hard to see the head stamp. Some of the letters are getting to read. But I will not shoot ammo that leaves ejector marks.

Yes I know some of Hornady's own factory loading are hot. I see the cases when I'm picking up range brass and a buddy who doesn't reload gives me his brass.

G

Maybe they are surprised because it doesn't happen with any real frequency?

I've never had one break...

But I will say I try to stay within the recommended pressures (by monitoring velocity) for the platform. I have shot some hand loads that were not over pressure until I screwed my can on. So I do load right on the edge, but I use velocity to tell me if at I'm getting close to max pressure.

6.5 Grendel Hornady brass...I have 25 to 30 of the first cases (over 2 years ago) I got for Grendel's. Last loading I lost 5 cases so they are now loaded as hunting ammo so i dont have to worry about recovering brass.

I've had good brass life by staying within recommended max velocities. I have cases where it's getting hard to see the head stamp. Some of the letters are getting to read. But I will not shoot ammo that leaves ejector marks.

Yes I know some of Hornady's own factory loading are hot. I see the cases when I'm picking up range brass and a buddy who doesn't reload gives me his brass.

Have had and been around many Grendels since they came out, and never have seen a broken bolt. I have a Maxim bolt that came with a Lilja barrel, it has over 5300 rounds through it, all suppresed and is still going strong. A good bolt and no over pressure loads a Grendel bolt will last the life of your barrel. People like buck just spread imaginary "facts" they read on the internet with no real world experience. Heck he can't even spell Gredel!

 

[Buck Fever]

There is at least one poster in this thread that has broken bolts. How many is too many?

People break 5.56 bolts all the time but that seems to be people running cheap BCGs and doing mag dumps all the time.

When you see Grendle (spelled just for you) bolts break and you know they are doing slow fire and probably not steel case ammo, how much margin is in the design?

When you see failures and you also see how they screwed it up, that's not good.

Propagating the same weakness over several cartridges is just bizarre.

 

[Frog4aday]

Maybe it's just best to view Grendel bolts as a wear and replace item, like a barrel. Get your thousand(s) of rounds out of it, and when (if?) it breaks, you get a new one. That doesn't seem too hard or expensive to do. Better than fighting over if it's a problem or not. If one breaks, you replace it. Now, if it was happening after a 100 rounds or something ridiculous like that, then it might be a consideration, but that doesn't seem to be the case.

As for the 6mm ARC, I'm happy to have it around as an option. One more low recoil but decent energy cartridge that can be use for deer sized game (and smaller) as well as being effective for competitive shooting seems like a good thing. Time will tell if it has legs. In the meantime, I'm going to keep enjoying my 'outdated and obsolete' 6.8 SPC II.