New 6mm AR-15 pressure tested wildcat cartridge! 6MM MAX

[No manches"]

What if someone doesn't want an upper?.
And desires a bolt gun?.

Do you or will you provide gunsmithing?..

 

[BCPB6mmMAX]

What if someone doesn't want an upper?.
And desires a bolt gun?.

Do you or will you provide gunsmithing?..

Yes

 

[David Milisock]

I hope you do realize that rebating the rim does not reduce bolt thrust. Granted, you probably have a small margin due to 5.56 vs the 223 saami 55000 psi max on the same platform, but it's hard to compare the two.
Here's a good article on bolt thrust, the real issue with AR15 bolt failures.

A Look at Bolt Lug Strength - Lilja

All action designers are concerned primarily with producing a safe and functional product. All other considerations such as weight, finish, eye appeal and other cosmetics are secondary. From a safety standpoint, the strength of the bolt lugs is of prime concern. Bolt lug shear strength depends...

riflebarrels.com

Exactly my question, I'm have a good time because of great performance with my 6 ARC but one needs to be aware of the limitations.

 

[David Milisock]

Hi all,
We are New to the forum and would like to introduce ourselves and our company . I’m Brian Cook and my partner is Mike Bueschel.
We are BC Precision Ballistics and our cartridge is the 6mm MAX.
We have unlocked the code for .378 bolt head performance. After 3 years designing and testing, to include lab pressure testing at EMRTC with Dave Emary, we knew we had a winner . Paul has given us the honor to introduce our cartridge first on accurate shooters .

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

Thanks for the post, I'm been a 40 year fan of the 6MM and will check out your site and information.

 

[BCPB6mmMAX]

Just a quick update for anyone interested.

110k pieces of 6mm MAX just arrived.
200 HBAR barrels ordered.
200 Lee and Lyman custom dies in stock.
Mark7 up and running for factory loaded ammo
20” AR Loads :58gr VMAX 3550FPS , 85gr Speer 3015FPS, 90gr ELDX 2825FPS
The wait is almost over…….

 

[benchrest]

very cool. i run a 20" 6x68 with 58gr vmax @ 3400fps. it can go higher but groups opened up and i started to trash brass a little quicker. if your brass & primer pockets can hold up to 3550fps for about 10 rounds, id say you have a winner.

 

[BCPB6mmMAX]

very cool. i run a 20" 6x68 with 58gr vmax @ 3400fps. it can go higher but groups opened up and i started to trash brass a little quicker. if your brass & primer pockets can hold up to 3550fps for about 10 rounds, id say you have a winner.

Our real speedster is the 55 nosler, it goes 3680FPS. Problem is getting them from nosler in large quantity for loading.
The 58gr vmax is a TAC powder load as well and makes 54k Psi , so it has normal brass life .

 

[itchyTF]

The primer pocket looks messed up in your last picture. Like extra brass where it shouldn’t be. Opposite the 6mm headstamp.

 

[BCPB6mmMAX]

The primer pocket looks messed up in your last picture. Like extra brass where it shouldn’t be. Opposite the 6mm headstamp.

Pictures are deceiving , that’s a shadow as I’m a terrible photographer especially with an iPhone.

 

[Twdmar]

Our real speedster is the 55 nosler, it goes 3680FPS. Problem is getting them from nosler in large quantity for loading.
The 58gr vmax is a TAC powder load as well and makes 54k Psi , so it has normal brass life .

I hope this works out like you're hoping. Have you considered necking down to 22 caliber? Seems like a 77gr would work well with your case.

 

[BCPB6mmMAX]

I hope this works out like you're hoping. Have you considered necking down to 22 caliber? Seems like a 77gr would work well with your case.

It’s Not out of the realm of possibilities.

 

[BCPBMike]

This morning Ray Helms posted a video review of our 6mm Max cartridge on his X-Ring YouTube channel. Click here to watch.

 

[Swift4Yotes]

I've shots thousands of rounds out of the 22 Nosler at max and near max loads and never had any case head issue that amounted to squat. I can not understand why people have such issues. I suppose most is bolt timing related and a gas system tuning issue as opposed to a brass/rebated rim issue.
Secondly our 24" 10 twist zero freebore 6 Hagars run 87s 3050 fps very happily and 70s at a shade over 3400. 60s are around 3530 and I'm not sure if I chronographed 80s and 65s. They all shoot very accurately and the 60 Sierra and 65 VMAX are .020 off the lands around that 2.260" to 2.265"oal. The 55 and 70 noslers are still .100 off at 2.295. Longer high bc bullets just eat powder capacity with the ar mag constraints. With that said imo the platform is best suited for 87ish grain and under bullets and should be throated and twisted for such. Then to make matters worse it seems most people then order a 16 to 20" barrel and loose any benefit of the larger powder capacity. Short barrels require bigger bores to reap the speed benefits. What you end with is a short range fast twist somewhat accurate rig advertised to shoot 1000 yards that is less accurate with the lighter bullets that the platform is better suited to shoot.

 

[BCPB6mmMAX]

I hope this works out like you're hoping. Have you considered necking down to 22 caliber? Seems like a 77gr would work well with your case.

Many folks have asked us to neck down to 22.
The 80-90 gr .223 projectiles have high BC. You never know what’s coming next ???

 

[Rocketvapor]

Neck it to 224, long throat barrels and call it the
22 Mini-Max

 

[Tesoro]

Thanks for your contribution to the shooting world!

 

[constructor]

The Tac 6 is another 6mm based on a shortened 6.8 case, been around since 2010, 95 SMK hits 2800 out of an 18" barrel using 6.8 bolts. Big brother is the TAC 30 (rimless 30 Herrett at AR pressures) it will push a MK319 130gr to 2600 out of a 16" barrel. The 6.8 bolts don't break like the Grendel and 7.62x39 bolts do.
Yes we have been loading to 2.295" since 2006 using Pri 6.8 mags then LWRC came out with the SIX8 and now we use 6.8 pmags that allow 2.31".

 

[BCPB6mmMAX]

Thanks for your contribution to the shooting world!

Your welcome!
We are going to update our reloading charts in 3 weeks to add additional powders and bullets.
We think you will like the additions.

 

[BCPB6mmMAX]

Neck it to 224, long throat barrels and call it the
22 Mini-Max
View attachment 1476705

With the mag room we have and case dimensions, my initial thoughts are that a long throat won’t be needed. It would have the performance of your 22 nosler long seated but mag fed.

 

[Rocketvapor]

Somebody around there must have a .223 neck die