Interesting.
- Thread starter nrspence
- Start date
Interesting.
....... Borrowed from the interwebs
Why The 6mm MAX?
The 6mm MAX is pressure tested to SAAMI standards of 55k psi. It is a brand new cartridge designed for the unmodified mil-spec .378 bolt face, and a full mass bolt carrier group. The 6mm MAX holds 35 grains of water capacity which ultimately determines the energy potential of the cartridge. In this case, 1750+Lbs of energy. Why is that so significant? The 6mm MAX can launch an 87 gr Berger VLD at 3009 fps from a 24” barrel. This produces 1749 lbs at the muzzle, 1504 lbs at 100 yards, 1093 lbs at 300 yards, 775 lbs at 500 yards, 533 lbs at 700 yards, and stays supersonic past 1000 yards. These ballistics are at standard atmospheric pressure and temperature.
Cartridge designers have struggled with 2.26 OAL, and having enough room for increased case capacity. Until recently, there hasn’t been a .378 case head cartridge available that has a 35 gr water capacity. This amount of water capacity is the engine that can power heavier, and high ballistics coefficient bullets up to 100 grs. The 6mm MAX can do this within the constraints of the AR-15, and function flawlessly. So the end result is that the 6mm MAX can push bullets 55 gr to 100 gr, and do it with the same 2.30 OAL. Some designs have emerged shorter and fatter to accommodate a bullet with better BC and enough powder for useful velocities. When comparing the water capacity of 24 Nosler (29 grs), 6.8 SPC (35 grs), 5.56 x45 NATO (28.5 grs), 6×45 (29 grs), 6 ARC (34 grs), 6.5 Grendel (35 grs), .224 Valkyrie (34.5 grs), and what do we get? For the cartridges with .378 case head, powder capacity is less than the 6mm MAX. For the cartridges with larger case heads, you get the same amount of powder or less than the 6mm MAX. The end result is that the 6mm MAX (35 grs) allows for a .378 mil-spec bolt face with full lug integrity and powder to push the heavies at useful velocities.
The 6mm MAX has unlocked the code on the .378 bolt face AR-15 cartridge. We were able to increase the OAL to 2.30 with the .350 Legend parent case, and magazine, which were originally designed for the AR-15, and function flawlessly. With the OAL set at 2.30 for all bullets 55 gr to 100 gr, we were able to keep bullet jump relatively consistent for the inherent accuracy across all bullet weights. We have been able to achieve 1 MOA accuracy with most bullet weights, and sub-MOA with premium target bullets.
BC Precision Ballistics has spent 3 years and thousands of hours in research and range time to get the 6mm MAX perfected. Our case is only slightly rebated for a well balanced cartridge maximizing capacity and 100% reliability. We designed the chamber for functionality in a repeater and for accuracy. Sometimes those two requirements conflict with each other as reliability requires loose tolerances, and accuracy requires tight tolerances. We consulted with many lifelong industry experts throughout the chamber/reamer design and listened to what they had to say. We utilize carbide reamers for our builds, and our tolerances are kept exact for predictable performance.
Wondering about accuracy? On Aug 6th, 2022, I competed with the 6mm MAX in F-Class with my local club the Central Texas Silhouette Association or CTSA. Full disclosure on me? I’m an old F-Open High Master. My normal competition gun is a .243 30” Bartlein barrel running 105 hybrids at 3050 fps with a stout load of H4831SC. The 6mm MAX is not a competitive F-Open cartridge by any stretch of the imagination, but I wanted to see an actual real world test of accuracy in the hot south Texas switching winds at 500 yards. I used a 24” Bartlein barreled hunting rig. This is the same bolt rifle pictured on this web site. It has 2600 rounds of testing down range, and is till holding sub-MOA with a load of H4895 tested to SAAMI standards of 53,000 psi. The load was 26.6 grs of H4895, and 90 gr Lapua Scenar-L at 2.30 OAL. This load was straight from our loading chart on this web site. After the 3rd relay my score was 568-6X. Nothing to write home about by F-Class standards, but in the world of hunting and rifle accuracy these rounds would have HARVESTED GAME.
The 6mm MAX velocities/load chart can be found on 6mmmax.Net
We are scheduled for more lab testing in Sep. 2022 at EMRTC to expand our powders and bullets as it has been struggle to find components the last two years.
Thanks
Brian Cook
6mmMAX.net
Why The 6mm MAX?
The 6mm MAX is pressure tested to SAAMI standards of 55k psi. It is a brand new cartridge designed for the unmodified mil-spec .378 bolt face, and a full mass bolt carrier group. The 6mm MAX holds 35 grains of water capacity which ultimately determines the energy potential of the cartridge. In this case, 1750+Lbs of energy. Why is that so significant? The 6mm MAX can launch an 87 gr Berger VLD at 3009 fps from a 24” barrel. This produces 1749 lbs at the muzzle, 1504 lbs at 100 yards, 1093 lbs at 300 yards, 775 lbs at 500 yards, 533 lbs at 700 yards, and stays supersonic past 1000 yards. These ballistics are at standard atmospheric pressure and temperature.
Cartridge designers have struggled with 2.26 OAL, and having enough room for increased case capacity. Until recently, there hasn’t been a .378 case head cartridge available that has a 35 gr water capacity. This amount of water capacity is the engine that can power heavier, and high ballistics coefficient bullets up to 100 grs. The 6mm MAX can do this within the constraints of the AR-15, and function flawlessly. So the end result is that the 6mm MAX can push bullets 55 gr to 100 gr, and do it with the same 2.30 OAL. Some designs have emerged shorter and fatter to accommodate a bullet with better BC and enough powder for useful velocities. When comparing the water capacity of 24 Nosler (29 grs), 6.8 SPC (35 grs), 5.56 x45 NATO (28.5 grs), 6×45 (29 grs), 6 ARC (34 grs), 6.5 Grendel (35 grs), .224 Valkyrie (34.5 grs), and what do we get? For the cartridges with .378 case head, powder capacity is less than the 6mm MAX. For the cartridges with larger case heads, you get the same amount of powder or less than the 6mm MAX. The end result is that the 6mm MAX (35 grs) allows for a .378 mil-spec bolt face with full lug integrity and powder to push the heavies at useful velocities.
The 6mm MAX has unlocked the code on the .378 bolt face AR-15 cartridge. We were able to increase the OAL to 2.30 with the .350 Legend parent case, and magazine, which were originally designed for the AR-15, and function flawlessly. With the OAL set at 2.30 for all bullets 55 gr to 100 gr, we were able to keep bullet jump relatively consistent for the inherent accuracy across all bullet weights. We have been able to achieve 1 MOA accuracy with most bullet weights, and sub-MOA with premium target bullets.
BC Precision Ballistics has spent 3 years and thousands of hours in research and range time to get the 6mm MAX perfected. Our case is only slightly rebated for a well balanced cartridge maximizing capacity and 100% reliability. We designed the chamber for functionality in a repeater and for accuracy. Sometimes those two requirements conflict with each other as reliability requires loose tolerances, and accuracy requires tight tolerances. We consulted with many lifelong industry experts throughout the chamber/reamer design and listened to what they had to say. We utilize carbide reamers for our builds, and our tolerances are kept exact for predictable performance.
Wondering about accuracy? On Aug 6th, 2022, I competed with the 6mm MAX in F-Class with my local club the Central Texas Silhouette Association or CTSA. Full disclosure on me? I’m an old F-Open High Master. My normal competition gun is a .243 30” Bartlein barrel running 105 hybrids at 3050 fps with a stout load of H4831SC. The 6mm MAX is not a competitive F-Open cartridge by any stretch of the imagination, but I wanted to see an actual real world test of accuracy in the hot south Texas switching winds at 500 yards. I used a 24” Bartlein barreled hunting rig. This is the same bolt rifle pictured on this web site. It has 2600 rounds of testing down range, and is till holding sub-MOA with a load of H4895 tested to SAAMI standards of 53,000 psi. The load was 26.6 grs of H4895, and 90 gr Lapua Scenar-L at 2.30 OAL. This load was straight from our loading chart on this web site. After the 3rd relay my score was 568-6X. Nothing to write home about by F-Class standards, but in the world of hunting and rifle accuracy these rounds would have HARVESTED GAME.
The 6mm MAX velocities/load chart can be found on 6mmmax.Net
We are scheduled for more lab testing in Sep. 2022 at EMRTC to expand our powders and bullets as it has been struggle to find components the last two years.
Thanks
Brian Cook
6mmMAX.net
Anytime someone starts describing a cartridge by touting fairly high velocity for a lighter than usual for caliber bullet using a longer than common barrel I either guess that it's an older guy interested in varminting/hunting, or it just can't do the bullet weights I'm interested in because of mag limitations. Or both of those things.
The SOLGW guys have spoken a few times on building rifles in this caliber and loading a lot of ammo for it. So I'm excited to see more about it.
I did find some 20in data
20” AR Loads :
58gr VMAX 3550FPS
85gr Speer 3015FPS
90gr ELDX 2825FPS
I'm really curious if this configuration will feed more reliably and magazines will function better than current 6mm AR offerings.
16” velocity needs to be published
Reminded me of when the 25-45 Sharps was announced, people saying it was a modern AR capable version of the .250-3000. Which I thought was a great comparison, lots of hype and they both only made the much touted velocity with one bullet weight.
6max case trim length 1.715"
Hard pass for me.
This appears to be about even with the ARC @87gr & may be better with under 87. It's a varmint round. I mean cool if that's what your after, but I like heavies.
This is the 6Max load for 95 Berger's from a 24" barrel. 100gr is the heaviest projectile they list.
My 6ARC with 30.4gr Lever & Berger 95 VLD's runs 2933 from a 22" barrel. That's the lightest projectile I've run in the ARC.
Kind of seems like a similar comparison as 22 nosler vs 224 Valk.
Faster with lt bullets, but case is to long for heavies.
Hard pass for me.
This appears to be about even with the ARC @87gr & may be better with under 87. It's a varmint round. I mean cool if that's what your after, but I like heavies.
This is the 6Max load for 95 Berger's from a 24" barrel. 100gr is the heaviest projectile they list.
My 6ARC with 30.4gr Lever & Berger 95 VLD's runs 2933 from a 22" barrel. That's the lightest projectile I've run in the ARC.
Kind of seems like a similar comparison as 22 nosler vs 224 Valk.
Faster with lt bullets, but case is to long for heavies.
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It seems to me the purpose of this cartridge is not to deliver superior ballistics over 6ARC.
Rather, it is to deliver nearly the same ballistic performance while having much greater durability and reliability in an AR platform.
I am interested.
Rather, it is to deliver nearly the same ballistic performance while having much greater durability and reliability in an AR platform.
I am interested.
Yeah, not a good way to start. At least the 6ARC they were talking about 12.5-18" barrels
At the very least, I just wish they would show me right off the bat:
How much more can you give me than 77gr BH red box 5.56/Mk262 level loads from a normal barrel length...probably 16-18?
IF they MAX can have me handily out-pacing 77gr 5.56mm with 90gr 6mm projo...or a 95gr load equal to or greater than 77gr out of an 18" or less barrel, then I'd consider it...especially not having to swap bolts and dick with fucked up magazine options.
Thought $1.50 sounded a little spicy, but I guess I haven't noticed what 6ARC had gotten up to.
Not quite sure what to think about added durabilty and reliabilty , there are bolts made to handle larger rims well enough.
6mmARTurbo 40 is about max you can push 6mm within Ar15 mag limitations has about 4+ grains on 6ARC case volume , and unlike many smaller rim cases it doesn't burry the bullet deep in the case.
6mmARTurbo 40 is about max you can push 6mm within Ar15 mag limitations has about 4+ grains on 6ARC case volume , and unlike many smaller rim cases it doesn't burry the bullet deep in the case.
I know there are feeding issues, but hasn't the 6x45 been around for a couple of years?
Mag feed Oal limitations with longer cases than grendel based ones.
From the limited info I've seen on this, the major advantage is the bolt face. Unlike the ARC, it uses the same bolt as a standard 556/223.
Apparently, the ARC can be hard on the bolt, with peening and cracking issues. Other than that, it sounds a lot like an ARC clone.
X-Ring did a video on it, he saw it as being a good choice as a DMR in those types of matches.
Apparently, the ARC can be hard on the bolt, with peening and cracking issues. Other than that, it sounds a lot like an ARC clone.
X-Ring did a video on it, he saw it as being a good choice as a DMR in those types of matches.
Test Barrel: Bartlein 24” Twist: 1/8 Tested to SAMMI Standards in Socorro, NM at EMRTC.
I agree they should have shortened that neck some to take advantage of the heavies too.....not like it aids in case capacity.
I made a wildcat of a wildcat to toy with in the AR myself. My reasoning is because i'm a cheapass lol. I like 223 brass as it's virtually free and LC brass is decent stuff.
I made the initial cartridge to be a full length 1.75" case and setup for the 105 class as a cheap cartridge to let my kids shoot and possibly build them a howa mini as their first deer rifle with it.
Took the AI concept but with a 30' shoulder then built the rest around the bullet. I have yet to spin up a barrel for the full length but did make a 14" barrel for an AR. And it's not too shabby. I got 2380 ft/sec but will likely throttle it down to 2350 as a buffer (live in AZ where it get's hot as balls)
I need to finish doing load dev and start shooting it more. I just have a couple oh I dunno 2-3 (ha!) irons in the fire
55gr 5.56 next to a 108 eldm in my 24 Mamba AR
I made a wildcat of a wildcat to toy with in the AR myself. My reasoning is because i'm a cheapass lol. I like 223 brass as it's virtually free and LC brass is decent stuff.
I made the initial cartridge to be a full length 1.75" case and setup for the 105 class as a cheap cartridge to let my kids shoot and possibly build them a howa mini as their first deer rifle with it.
Took the AI concept but with a 30' shoulder then built the rest around the bullet. I have yet to spin up a barrel for the full length but did make a 14" barrel for an AR. And it's not too shabby. I got 2380 ft/sec but will likely throttle it down to 2350 as a buffer (live in AZ where it get's hot as balls)
I need to finish doing load dev and start shooting it more. I just have a couple oh I dunno 2-3 (ha!) irons in the fire
55gr 5.56 next to a 108 eldm in my 24 Mamba AR
How does the 6 Max compare with a 6x45 with bullets up to the 90 gr range?
Yes, the winds at CTSA are challenging.
A buddy of mine did that with the .221 Fireball Improved, shooting long .224” bullets as a training rifle in the Howa Mini action.I agree they should have shortened that neck some to take advantage of the heavies too.....not like it aids in case capacity.
I made a wildcat of a wildcat to toy with in the AR myself. My reasoning is because i'm a cheapass lol. I like 223 brass as it's virtually free and LC brass is decent stuff.
I made the initial cartridge to be a full length 1.75" case and setup for the 105 class as a cheap cartridge to let my kids shoot and possibly build them a howa mini as their first deer rifle with it.
Took the AI concept but with a 30' shoulder then built the rest around the bullet. I have yet to spin up a barrel for the full length but did make a 14" barrel for an AR. And it's not too shabby. I got 2380 ft/sec but will likely throttle it down to 2350 as a buffer (live in AZ where it get's hot as balls)
I need to finish doing load dev and start shooting it more. I just have a couple oh I dunno 2-3 (ha!) irons in the fire
55gr 5.56 next to a 108 eldm in my 24 Mamba AR
I really wish the AR-15 had stayed with a shortened .222 case at around 1.600", but in either .243 or .257 bore and 30˚ shoulder. Leave room for long ogive bullets and punt them out with faster powder to meet the SCHV requirements, but retain momentum better with higher BCs. You could still have a lightweight assault rifle load in the 55-75gr region screaming along at 3000fps, DM loads with higher BC at 2700-2800fps.
First thing I asked about 6mm Max was, what’s different about this compared to 6x45?
Other cartridges that have come and gone for the AR-15 include:
22 Nosler
6mm Hagar (screamer but no high BC bullets)
25x45 Sharps
30 RAR
At first I was aggravated with the introduction of this. Now I no longer am. I am glad that I have my Grendles and 6mmAR and ARC. Wasn't totally aware of having to use the lighter projectiles and a 24" barrel. I'm into my shorter barrels and heavier weights. I am good with my decisions. 14.5 ARC and 12.5 Grendle's in my near future!
The AR was originally intended to be chambered in the .222 Mag. For reasons unknown to me (perhaps tooling had already been purchased that would have been expensive to replace?) the magazine and BCG were not lengthened to the necessary length and so we wound up with the 5.56 NATO.
IMO the 6 ARC was a missed opportunity. The barrel extension and bolt should have been redesigned to handle appropriate pressures and bolt thrust. As the idea was essentially a parts bin project the gun could not handle bolt thrust of typical pressures of a 6 PPC. So they went with a shortened version to prevent chambering of a 6 PPC.
Back to the 6 Max, it seems to solve most, if not all, of those problems. Brass availability long term is critical. I’m guessing Starline made a special run. Acceptance of the cartridge will tell the tale.
I’d be interested to see how your project progresses compared to a 6x45 with 90gr and lighter bullets. I’m aware of a couple of people shooting 6x45s in bolt guns and 90gr pills seem to be about as heavy as they can keep velocities up with the available powder capacity.
Have you run some simulations with the internal ballistics program?
Cheers
The Army was basically having Stoner run around in circles with engineering studies and drafts for all the different cartridge configurations and subsequent rifle and magazine design changes while they pushed forward with getting the M14 type classified and adopted as the new official service rifle, especially after seeing the traction that was building from the head-to-head tests at Benning with the AR-15 and hand-selected M14s.
There was at least one engineer in Ordnance Board who thought a necked-down .25 Remington would have been more ideal, but it would have sent Stoner on another goose chase.
The .221 Fireball and .222 Remington get a lot of work done from shorter propellant columns, which is more efficient. I’m not a fan of increasing the propellant mass by length without also increasing case diameter.
For me, after seeing how anemic 6mms of all flavors are at distance, I just can’t get excited about any of them. I shoot steel a lot, so I’ve always been disappointed by 6mm impacts once you start getting out to 600 and farther, which is already a boring distance to shoot at with shorter 6.5mm Grendels. All of them hit hard at 300yds and in, which is child’s play distance for me. I often will just skip past the 400yds 12” steel out of boredom even with the 12” piped Grendel.
If I can shoot that 90gr ELDX out an 18" SPR and see 2750-2775fps I'm game.
5.56 77SMK 2750fps from 18" is very common, and max pressure.
A 90gr .243 moving the same velocity with 13gr more weight, .243 dia, higher BC and utilizing same BCG and 5.56 mags? Yup!
Don’t forget that the M-16 was first adopted by USAF for Air Base defense which is essentially light infantry that aren’t heavy on that type of training.
Just for comparison I'm getting 95gr SMK up to 2887 fps using H4895 out of a 22" in my 6mmFatRat. Haven't tried LeverRever but maybe get the speed to almost mid 2900's??
I ditched the 105's because there is noticeably more recoil and the also wind drift is the same because of the lower fps of the 105.
6mmFatRat/ I've outshot friends on steel at 1000Y with bigger guns on windy days because of the advantage of quick follow up shots. I hadn't imagined I would but they couldn't keep up with the rapidly changing condiitions.
Also I won a night match going out to almost 900Y at least once, or maybe twice??, with my 6mmART40 against the normal 6 and 6.5 bolt guns.
Darn capable little rounds they are and haven't busted a lug yet.
Not quite sure I'm willing to change over to 6mmMAX.
I ditched the 105's because there is noticeably more recoil and the also wind drift is the same because of the lower fps of the 105.
6mmFatRat/ I've outshot friends on steel at 1000Y with bigger guns on windy days because of the advantage of quick follow up shots. I hadn't imagined I would but they couldn't keep up with the rapidly changing condiitions.
Also I won a night match going out to almost 900Y at least once, or maybe twice??, with my 6mmART40 against the normal 6 and 6.5 bolt guns.
Darn capable little rounds they are and haven't busted a lug yet.
Not quite sure I'm willing to change over to 6mmMAX.
Maybe SIG could be talked into making a strengthened bolt for a spear light in 6 ARC? Much like the lugs and metalurgy of the bolt and barrel for the 6.8 hybrid round in the XM7. That should allow equal pressures to bolt action loads. Maybe even a hybrid cased version of 6 ARC for even higher pressures and heavier low drag rounds or insanely high speeds with lighter rounds?
US Army ceased ordering spare parts for the M2 Carbines after Korea, so USAF SPs were left with no projected logistics support for their primary weapons guarding the all-important SAC bases and nuclear-equipped strategic bombers. General Curtis LeMay was looking for a replacement for the M2 Carbines even when he was USAF Vice Chief of Staff from 1957-1961, which coincided with the AR-15s early development and 601 Production, which started in 1959 at Colt.
The famous Maryland 4th of July BBQ with LeMay present and the AR-15 for test-firing on watermelons seems to have been a pivotal moment in the AR-15 history. Nobody was going to get in the way of anything LeMay wanted, so when he announced on the spot that this would be the USAF’s next rifle, not even the Army Ordnance Board could stop it. They had just sent an evaluation to the Pentagon mere weeks prior to that declaring the AR-15 totally unsuitable for military service.
Dr. Carten was shocked when he got the reply from the Pentagon to begin military standardization and type classification of the AR-15 at the USAF’s request. USAF’s first contract was March of 1962.
I would never describe SPs as essentially light infantry though. Under LeMay’s vision, they were elite perimeter defense security police tasked with preventing Soviet saboteurs from successfully attacking SAC bases. You could still see a sense of high professionalism and no-BS attitude in SPs at least into the 1990s. They didn’t screw around in the 1970s and 1980s either.
What I’ve seen lately is not inspiring.
That looks like a lengthened 24 Nosler. Look at the case diameter and what appears to be a rebated rim that looks just like 22 and 24 Nosler case geometry. 24 Nosler has a shorter case at 1.600”.
So if they’re using 350 Legend parent case, then it’s not quite the 24 Nosler, which has .378” head/.420” body.
350 Legend has .378” head, .390” body.
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.224 Springfield was meant for the Springfield Armory SCHV Rifle submission, not the ArmaLite AR-15. The AR-15 was first built on 222 Remington testing, which then had the shoulder blown forward and case lengthened to get more mv for the SCHV submissions and the moving goal posts of the steel helmet perforation requirements.
.222 Rem Mag was the commercial market offering of the .224 Springfield.
I imagine he’s shooting 90gr for that 2750fps in 16” barrel. 18” should put it 2775-2800ish. I like it! When compared to the 77SMK 5.56.
90gr ELD-X from an 18” will be doing 2754fps avg based on their 24” published data.
Using Hornady’s doppler program with that bullet, it goes subsonic between 850-875yds.
With 90gr Berger (same published BCs as the 90gr ELD-X), they showed 120fps mv slower than the Hornady bullet.
90gr 6mm, .409 G1 BC reference (actual doppler track data used), 2754fps mv
500yds +3 mils 1.3 mils drift 1735fps 602ft-lbs
600yds +4.2mils 1.6 mils drift 1558fps 485ft-lbs
700yds +5.7 mils 2 mils drift 1392fps 387ft-lbs
850yds +8.4 mils 2.7 mils drift 1161fps 269ft-lbs
At 2500 DA my 6mmFatRat load posted earlier goes subsonic around 1300 yards but mine has a 22" 8 twist barrel.
LRR, what's your 6.5G load and when does yours go subsonic?
LRR, what's your 6.5G load and when does yours go subsonic?
I have 7 Grendels, but I shoot the 12” the most lately. Any time I take it out, I take the 17.6” Lilja too.
My CFE223 load (well below 50,000psi in the pressure test breach, below book max) under a 123gr Hornady A-MAX averages 2490fps 15ft from the muzzle out of the 17.6” pipe. Brass ejects looking almost new.
At sea level, Hornady’s doppler program says:
500yds +3.6 mils 1.3 mils drift 1632fps 728ft-lbs
700yds +6.7 mils 2.0 mils drift 1329fps 482ft-lbs
800yds +8.6 mils 2.4 mils drop 1189fps 386ft-lbs
850yds +9.7 mils 2.7 mils drift 1125fps 345ft-lbs
At my main altitude (6300ft), I’m supersonic to 1250yds with the ELD-M or A-MAX.
With 123gr Scenar or 123gr SMK, it changes quite a bit.
1000yds 10.3 mils drop 2.2 drift 1332fps 485ft-lbs
1200yds 1144fps 358ft-lbs
1300yds 1087fps 323ft-lbs
I’m supersonic past 1300yds with them from the 17.6”, but that 6mm Max would be too up here, just hits with 6mm tiny “tink”.
I like seeing my impacts and hearing them. I’ve rapid-fired that 123gr A-MAX load at 1000yds on the big gong first time I shot it through the 17.6” Lilja at 1000yds, and they stacked within 8” vertical, 4” horizontal. That stick is so lightweight, it feels like a pre-SOCOM barrel profile M4 with the original 727 cut, really light under the handguard at .650”, then steps up to .750”/.740” to the muzzle.
The 130gr 6.5mm ELD-M doppler data says it will be supersonic well past 1400yds from the 17.6” barrel.
130gr Nosler RDF has an even higher BC than the 130gr ELD-M or Bergers, so it’s been on the back-burner to load, but I’ve been shooting factory ammo almost exclusively lately. Mainly 123gr ELD-M and that 110gr PPU, which is really flat.
The 130gr RDF should stay super out to 1500yds. Even from a 12”, it will have insane supersonic reach up here at over 1400yds. At sea level, it will stay super to 1000yds even if only shot at 2290fps. That’s using G7 drag model.
I like having 25rd mags too. If I want to shoot 90gr, I can do that too and punt them out fast. Factory Federal 90gr does 2700fps from the 12” Grendel, 2900fps from the 17.6”. BC is higher on the 6mm 90gr though, but going about 150fps slower from same barrel length.
6mm Max seems like what SCHV should have been for a great lightweight service rifle in the late 1950s, to go forward in military service over the following decades. Would make a great Assault Rifle, DM, and LMG cartridge with better downrange performance than 5.56 for sure.
Mags would have been a little bit taller as one minor drawback, but the cases are only 12 thousandths larger in diameter than 5.56, adding only ~0.36” inches to the cartridge stack. You would still be able to get a 65gr over 3100fps from a 14.5” carbine too. 20” would do 3290fps.
20” would spit that 70gr load out at 3245fps
14.5” would do 3066fps with 70gr....
That would be a sick assault rifle cartridge.
Mags would have been a little bit taller as one minor drawback, but the cases are only 12 thousandths larger in diameter than 5.56, adding only ~0.36” inches to the cartridge stack. You would still be able to get a 65gr over 3100fps from a 14.5” carbine too. 20” would do 3290fps.
20” would spit that 70gr load out at 3245fps
14.5” would do 3066fps with 70gr....
That would be a sick assault rifle cartridge.
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Nope, you have that backwards. The 6mm ARC is longer than the PPC, with the shoulder being .040" farther forward.
You might have confused that with the Grendel case; the 6mm ARC is shortened .030" from the Grendel (IMO purely to pretend they made a "new" cartridge compared to all the 6mm Grendel wildcats already in existence for 10+ years prior.)
You can't load a 6mm Grendel wildcat into the 6mm ARC barrel, but a 6 PPC does fit, although with too much headspace to even fire. You're off the mark on the pressure thing too; 6mm ARC/Grendel bolts do handle the pressure, it's the brass that is the weak link. PPC/Grendel/ARC cases all share the same internal design with very little case web compared to most high pressure cases.
Pretty good!
The extra wack the 6.5's give is fun on steel.
Years ago I got the 115DTACS to 2675 fps in my 6mmART40 with a 26" barrel. I think they had a .590G1 with the closed hollow point version. I had a 8 twist then so it was only an experiment but they shot well to 300Y.
I live at 7000 ft so in the summer at 8000 DA I'm going subsonic at 1500 fps. Might be able to extend that with A-Tips and Lever but I'm happy with those 95's.
Can only expect so much from a small frame.
77SMK IMI Razor Core drop test today with these atmospherics: 905yds test
Switch to 6mm Max inputs same atmospherics:
Switch to 6mm Max inputs same atmospherics:
No. The neck down was tried and ogive vs. magazine lengths didn't play well with each other.
Uh, what? Where did you hear that BS?
6mm Grendel wildcats have been around pretty much since the Grendel came out. They work great, which I can attest to personally with thousands of rounds through them using a bunch of different mags.
Don’t believe everything the Hornady marketing group tells you. Especially when a whole bunch of people here have personal experience contradicting it. All you have to do is read older threads about the 6mm Grendel wildcats from before the 6 ARC came out. Nobody anywhere was talking about needing to shorten the case.
Ogive length .740"
OAL cartridge 2.250"
2.250-.740= 1.510
Grendel case length: 1.520
ARC case length: 1.490
The cartridge wasn't intended for commercial release in the beginning and the projectile design for the original customer required what they required and everything else followed suit.
I bet a 90gr cruises 2775-2800 in an 18" if they cruise 2750 in a 16". 25fps per 1" is not out of realm at all.
Can confirm, Grendel necked down to 6mm with no other changes absolutely works fine.
Anybody making dies? I might have missed that part.
With a good chunk of the bullets out there, sure. With some of the heavies, no. With particular bullets, it was tested, didn't fit and/or related issues were found. You can make arguments either way, but the shoulder push back on the ARC had a design purpose that was the result of thorough testing, not for our own entertainment.
What bullets? Chances are I've tried them.
Just went and looked, 110SMK and 112 Matchburners fit with the ogive just past the neck at 2.26" OAL. If you have mags that allow 2.3" (as you should with this type of round) they both fit with plenty of wiggle room.
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I figured out what I want this cartridge for. A 22 Max wildcat. Neck it down and shoot 80ELD's at 2850 from a 16" barrel. I'm more interested in a (relatively) high BC .224 than a medium BC .243.
106 TAP/A-tip was the main driver, but there are others. Good for you if you can make them work. It was tested across several mfg. barrels, rifles, and magazines and we found issues that weren't acceptable for mass-scale ammunition production and the end results in the field. We've got tens and tens of thousands of rounds sunk into testing this. For one guy with one rifle to get everything tuned in with reloads, you have a lot of options available to you. If you're issued a rifle and ammunition, you don't.
It's similar to the .224 Valkyrie and 88-90gr projectiles. You can barely fit them at magazine length. Some people can make them work, but the bulk of factory ammo "sucks". Then, *magically* when you seat them long and/or in a bolt gun they hammer.... It's not the components that suck, it's the arrangement. When all you do is hand-load for a rifle that's one thing, when you have to produce accurate factory ammunition for an array of factory rifles there are trade-offs that happen that chip off the peak of what is possible to a skilled handloader with a custom rifle, but make the overall system function much better for the masses. Another .260 vs. 6.5 Creedmoor debate. At the end of the day, the SAAMI spec. solution functions better and gives more consistent results across a spectrum of rifle/barrels.
