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6mm max
- Thread starter nrspence
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Focusing on my 18” 708AR Rig. 139SSTs cruising 2750fps 55F. While I wait to see this 6MAX come to fruition. 
I’ve been thinking about a 7mm-08 AR-10 for a while. It would be cool in the Savage MSR-10 or one of the SFARs I think.Focusing on my 18” 708AR Rig. 139SSTs cruising 2750fps 55F. While I wait to see this 6MAX come to fruition.
Would be fun just because.
Mine has been a hoot. WC barrel, Aero receivers, TT diamond.
120gr Hammer hunters & Barnes TTSX @ 2880fps (N135 & TAC)
139/140gr Sierra & Hornady not far behind with 2750fps ish (N540) Initial testing a of last week with the 140s.
The 120s have light recoil and make hammer strings easy as 5.56 strings. The 140s aren't too much more felt recoil and I figure I'll see if the juice is worth the squeeze. 140gr at 800-1000yds got to do better than 120gr. Hope so, got 500ct 139SSTs coming today!
Most of the guys with the clogged gas tubes were competitors running factory ammo, many were suppressed with longer than typical gas systems as well. (maybe some running handloads with Lever, I didn't poll everyone who reported the issues) The factory powder is not only dirty, but based on chrono data, not temp stable. As far as bolts, the guys in the south were getting much higher velocities in the heat, so it could be assumed to be well over pressure, and might be a contributor to the bolt issues, also many of the reported velocities of handloads are well over book max, and likely over pressure...who knows without dissecting each issue. The recently announced 22 ARC claims temp stable powders, so I would imagine we will see 6mm ARC ammo offering with a temp stable powder as well. I run un-suppressed with handloads using a temp stable powder, so I am not seeing gas system issues. I get a lot of "why is your brass so clean" comments.
It would be interesting to see which bolts they were using.
Extended Length Gas Systems should mitigate any excess fouling, not promote it, because the port is farther away from the chamber. That results in less port pressure. Stepping down in bore volume will increase port pressure at comparable lengths. Running suppressed is just a dirty affair no matter what you do.
My unsuppressed 6.5 Grendel loads eject brass that looks better than new, especially with Lapua brass. Suppressed looks like steel case.
Extended Length Gas Systems should mitigate any excess fouling, not promote it, because the port is farther away from the chamber. That results in less port pressure. Stepping down in bore volume will increase port pressure at comparable lengths. Running suppressed is just a dirty affair no matter what you do.
My unsuppressed 6.5 Grendel loads eject brass that looks better than new, especially with Lapua brass. Suppressed looks like steel case.
Yeah, I was under the impression that the gas tube issues were due to the dirty factory ammo combined with barrel manufacturers using gas lengths based on 5.56 loads. The barrel manufacturers involved in the cartridge development seemed to use appropriate gas lengths, like the 16” Proofs using rifle gas lengths.
This round is doomed. Didn't make the announcement date, limited barrels and equipment. 22 ARC hitting at same time...
Long review of the 6mm Max vs. the 6 ARC for DMR competitions.
Looks fun!
Ol'boy talking about the need for weights on the gun and such. I was thinking about my 708AR is already slightly heavier and with 120gr pills the recoil is not bad at all. Hmmm.
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This......
Maybe someone can educate me. Being a long time 6DTI owner (6X6.8 Improved). I don't get where the 6 MAX or even ARC is doing things that hasn't been done many years before. Maybe it's just all about marketing and getting backing for new AR shooters. I don't think seasoned AR guys are going to fall for this, but again, educate me.
To me, the interest in 6MAX is using a 223 bolt vs using "non-standard" bolts for the 6.8/224V and 65G/ARC
Yup. I don’t have time to load for an entire cartridge in my supplies. I only load ammo for competitions in calibers for which I can also get factory loads. If there’s little to no factory support for a cartridge, then I’m not even going to entertain it. I yet to find one good enough to dedicate time for.
I thought 224 Grendel was good enough to sacrifice factory ammo. Then Hornady pushed the shoulder back 30 thou and commercialized the 22ARC. FML…
Initial reports from the testers
1. Lower recoil
2. Cleaner than 6arc
3. Uses a standard bolt
4. The heavier loads are basically the same as 6arc for elevation
I think 2 of the winners of the quantified performance match were using 6mm max
Having broken an extractor on a 6.5 Grendel build after maybe 150 rounds, I welcome any attempt to utilize the standard bolt assembly.
My main concern with this is whether or not the straight walled cartridge will impede loading and extraction in any way. Although I may point out that tailstock centers on a lathe are held in place via taper friction lock. Those require axial force to overcome friction to remove, so it's interesting to me that the industry standard is to use a tapered case for any modern rifle.
I do wonder if it wouldn't be better to use a 22 cal bullet like others have said. Why not try to get the highest BC bullet possible that fits in the COAL limit? Would that not be easier with the 22 cal class of bullets? Call it 5.56 MIN.
Lastly, I'm looking forward to someone necking this up to 30 cal and calling it .300 WWE SMACKDOWN.
My main concern with this is whether or not the straight walled cartridge will impede loading and extraction in any way. Although I may point out that tailstock centers on a lathe are held in place via taper friction lock. Those require axial force to overcome friction to remove, so it's interesting to me that the industry standard is to use a tapered case for any modern rifle.
I do wonder if it wouldn't be better to use a 22 cal bullet like others have said. Why not try to get the highest BC bullet possible that fits in the COAL limit? Would that not be easier with the 22 cal class of bullets? Call it 5.56 MIN.
Lastly, I'm looking forward to someone necking this up to 30 cal and calling it .300 WWE SMACKDOWN.
Well, the 350 legend case is straight walled, but the walls are not perpendicular. There is a taper to it, which aids in extraction. Just not as much taper as we typically see.
I realize 6x45 has had factory ammo, but it never took off and seems to have withered away.
Now, maybe the same thing will happen to 6 MAX. But, that’s for time to tell.
There are many other cartridges that are ballistically superior to this 6MAX, but when considering the abuse the cartridge has on the gun, as mentioned in the video, the 6MAX appears "softer" on the guts of the gun.
Now I would like to see 18-20" versions and shooting the 90-103gr 6mm bullets!
To much hit and miss on extraction in AR's as is why I didn't go 22 or 24 Nosler let alone 284win. Plus there wasn't anyone near me to check/test their guns. Oh, the reliable www.
I actually worked up a .257 based on the .224Valkyrie case that produces 2600fps from 110gr ELD-x & 110gr GameChangers , 2800+ fps with 100gr Nosler BT & Partitions and 2900+fps with Speer 87gr TNTs & HotCores and Sierra’s 90gr Bltitzking projectiles… this is the most consistent cartridge that I’ve ever worked with by providing single digit SDs across a large range of powders… all data was derived from three 20” X-Caliber barrels. JGS made the reamer with an elongated throat. .250 GLX (Goldilox) …. The word compromise is something that most shooters don’t want to hear but the fact is we’re adapting a cartridge to an old platform…. Very much improved platform but “OLD” nevertheless. Goldilox = BEST Compromise!!!
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Roger.
My 350L AR upper has never had a problem with that. Doesn't mean it can't happen, but this gives me some hope for the 6max using the same rim.
The.250Glx is getting a Redux… as the .250GlxRx aka the “Remedy “! I saw a trend during the work-ups that said a little more can be achieved with the concept!!! Very promising!!
Sadly this was the same issue with the .224 Valkyrie…. I hope that they will not make the same mistake with the .22ARC because it uses powders in the 4350 burn range…. Slower burn rate on a small bore diameter barrel absolutely will affect your dwell time in comparison with powders used for 5.56 platforms … I still believe that the industry doesn’t understand how the AR15 works….
This is a sign that powder is being pushed into the gas system prematurely and unburned. A longer gas system will be required…… to the industry “it’s not that hard!” Please put the sales people in the back seat!!!
It’s baffling to me. Barrel manufacturers only needed to look at what Proof was doing. Proof was involved with Hornady during the cartridge development and they went with intermediate length for 14.5” barrels, rifle length gas in 16” and rifle+1 in 18/20” barrels. Proof did most of the R&D for them and they just had to try some gas port sizes. But so many manufacturers decided to immediately try something different from the recipe developed during the cartridge R&D. It’s okay to think outside the box, but you need to have a solid understanding of inside the box operations first.
I think this has more interest/application from/for predator hunters that want a little extra boost over the 6x45 and 223/556.
22 MAX with a new Hornady 62 ELD-Vt on predators or even an 80.5 FB for comps is more interesting to me than a 6 Max with an 87 VLD
22 MAX with a new Hornady 62 ELD-Vt on predators or even an 80.5 FB for comps is more interesting to me than a 6 Max with an 87 VLD
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I don't have the gas system specs but he mentions at the end of the video that for this cartridge there is nothing special that needs to be done for reliability it's just like a normal AR. Then he shoots some full auto
Starline makes awesome consistent (.224 Valkyrie)brass for those considering wildcatting 6.8 based cases with long, high BC bullets…. Just saying! It gives you more capacity than 5.56 cases and short enough to use long projectiles . The gentleman that created the 6mm Max gives a volume comparison of the naming AR15 parent cases
You actually saw 3165fps out of a 55 from a 10.5" barrel? That seems absurdly fast for a barrel that short.
Kind of the point and you can literally see the Garmin showing those numbers in real time. Would be interested to know more details on powder and other load data. I've seen them, first hand, get velocities over 4K out of longer barrels while testing. Thinking really hard about running the 6 Max out of my SBR. I already use a lot of the popular powders for 6 Max. If I can get an extra 250-300 fps out of a 77gr. pill vs. 5.56 in a 12.5" barrel, I'm pretty much sold. The only thing holding me back is magazine capacity, dies, brass availability, the little things.
Maybe it was blinded by the fucking Yuge fireballs.
Looks like he wasn't allowing the unit to reset between shots on those dropped shots.
admittedly I haven’t read all 3 pages of this yet. I love the idea of a Superformance cartridge in an off the shelf AR15 sans barrel.
My immediate thought on this 6MAX is why the neck is so long?
Trim that neck down by a 1/3 or more, seat the projectile .05” lower and now it fits standard polymer 5.56 mags.
Or am I missing something?
Just to be transparent, I am pretty new at reloading, but am an avid studier and fascinated with wildcat cartridges.
My immediate thought on this 6MAX is why the neck is so long?
Trim that neck down by a 1/3 or more, seat the projectile .05” lower and now it fits standard polymer 5.56 mags.
Or am I missing something?
Just to be transparent, I am pretty new at reloading, but am an avid studier and fascinated with wildcat cartridges.
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As with so many new cartridges, I think the factor that will make or break this will be ammo pricing/availability. If the only ammo available is $1.5/rd from boutique companies, that pretty much guarantees this will only be popular with handloaders. If you are the type to handload for a rifle, the slight performance gain from a 6ARC might be a big deal, while the extra tuning needed for a 6ARC is likely less of a factor than it would be for the average shooter. Similarly someone looking into this for hunting could get the same performance with a 6ARC, and they aren't going to be putting the volume downrange to where the improved durability is a major factor.
I could see this cartridge really taking off if they manage to get ammo production going with a high-volume ammo manufacturer. If they got PSA to produce FMJ ammo, it would overnight become cheaper to shoot than 6.5 grendel or ARC, and immediately become an attractive high-performance 5.56 alternative to a whole lot of people. Similarly PSA could produce lower priced guns and barrels for those that don't want to spend SOLGW money.
I could see this cartridge really taking off if they manage to get ammo production going with a high-volume ammo manufacturer. If they got PSA to produce FMJ ammo, it would overnight become cheaper to shoot than 6.5 grendel or ARC, and immediately become an attractive high-performance 5.56 alternative to a whole lot of people. Similarly PSA could produce lower priced guns and barrels for those that don't want to spend SOLGW money.
Would .05” really affect the fps that much? I’m guessing 50fps at most.
And please, this is an honest question. In no way trying to be a jackass or argue. I’m genuinely trying to learn before I experiment and accidentally blow off some digits
Yeah no worries! It could absolutely affect things, especially with a hot or compressed load. It's not about the fps but the case pressure which can change drastically with seating depth. I've experienced this first hand where just a few thousandths can lead to pressure signs. And part of it is you WANT a longer COAL and less of a jump to the lands. There's also neck tension which is influenced by neck length to a certain degree.
So what mags are available to run a 2.29" OAL round in an off the shelf lower? Seems like if you don't have that available to you then you're stuck using lighter/lower BC projectiles and/or running the heavies slower due to the lost case capacity, thereby giving up any benefits.
ETA: It's stated in the article, duh, haha
However, to gain additional performance in 6mm MAX, the designers chose to use the already-available .350 Legend magazine design, which provides for a slightly longer 2.30" COAL and uses follower and feed-lip geometry already designed for the case body.
Can anyone with 350L AR mags confirm this OAL is doable?
ETA: It's stated in the article, duh, haha
However, to gain additional performance in 6mm MAX, the designers chose to use the already-available .350 Legend magazine design, which provides for a slightly longer 2.30" COAL and uses follower and feed-lip geometry already designed for the case body.
Can anyone with 350L AR mags confirm this OAL is doable?
I might have a Wilson Combat modified 350L Lancer mag. If so I'll get some measurements for viability. I could/can get 18rnds of 350L in those mags too.
