Grendel Magnum!!!

There was another thread on advanced powder - I suggested a Grendel Magnum.

Now...how to create an AR that can handle a Grendel Magnum?

Gas Block:

First, I think an adjustable gas block - turn it off and single load Grendel Magnum rounds. The Grendel Magnum cartridge could use the same case with a COAL that is too long to fit in an AR15 magazine - thereby mandating single loading of rounds.

Bolt:

The current bolt design on AR's has always bothered me a bit. Why the long locking lugs (height greater than width)? It seems that all the shear force will still occur at the lug base where the lug meets the circular outer bolt face. The long lugs should also be creating greater torque than a short lug would at that lug/outer bolt junction.

Why not increase the diameter of the outer area of the bolt with the result of shorter lugs (the overall diameter from end to end of the lugs remains the same)? The shear strain should be the same and the torque strain less. The bolt itself should be stronger as it would have a thicker wall around the cartridge head. Modification of the barrel locking lugs would be easy - just machine out the center to the new diameter.

I had thought about fewer but larger lugs but, that would require redesign of the carrier to rotate the bolt a bit more to disengage. It would also require redesign of the barrel locking lugs rather than just machining out the center diameter a bit.

Carrier:

One change on the carrier may be useful in my opinion. Lengthen the slot that rotates the bolt head - this would cause the bolt to stay locked longer as the carrier is moving rearward (similar result to the Tubb carrier weight system).

What are your opinions? To withstand higher pressures would stronger lugs be needed or keeping the bolt locked longer or both or something more?

Chamber:

To accomodate the longer COAL the barrel could be changed to a "jump to lands" design. The jump to the lands should also alleviate some of the initial pressure issues (as with 6.8s designed for higher pressure). While we are at it, why not progressive twist rifling as well to ease the transition from smooth bore to rifling.

Cartridge:

What safety measures need to be taken with a Grendel Magnum cartridge?
Is COAL greater than magazine length with well marked ammo boxes enough or is there a requirement for something more to prevent loading Magnum ammo in a standard Grendel? Or just call it +P and say "not rated for +P ammunition" on standard Grendels?

What kind of velocity could we get with a 60,000 psi cartridge pushing a 130 gr bullet loaded to longer than mag length?

Being a forum thread, this is mostly for fun but I am interested in hearing opinions. :)

Or you could just give DTEC a check and walk away with a 6.5WSSM AR. He builds 243WSSMs and 25WSSMs but I'm sure he could chamber one in 6.5mm. http://www.dtechsuperstore.com/WSSM%20page.htm

IIRC, he will not build 6.5WSSM because it has not been certified by Olympic Arms.

Reginhild, I love these concept threads, but personally I cannot see the point if it is single-load only.

It could be a mag-fed Magnum with longer bolt lock time - but would there be issues with Magnum ammo being identical to standard ammo?

With long Magnum rounds, it would be single fed for Magnums only and mag-fed for standard rounds.

Or you could just give DTEC a check and walk away with a 6.5WSSM AR. He builds 243WSSMs and 25WSSMs but I'm sure he could chamber one in 6.5mm. http://www.dtechsuperstore.com/WSSM%20page.htm

What changes does he make to handle the .300 WSSM?

Reg,

Unless you're talking about having this system on an AR15, it's already been made on the AR10...just about:

AR10 Short Magnum New Rifles or barrel conversions.
When accuracy is everything! We are Accuracy!


Long Before the Big boys even dreamed about an AR10 short magnum rifle, Accuracy Systems envisioned this great union of rifle and cartridge back in 2000. Being first gives you the advantage because we stumbled through the bugs corrected them and know what make these rifles tick. By the way they also tack as in tack driver! Some Smiths out there will say yes we can convert an AR 10 for you, But beware! Do you want someone who does a few rifles a year working on you high dollar piece or a company that has done quite many? By the way you will find our rifles reasonably priced compared to other companies out there doing custom AR10 work. In fact our rifles are in line with what Armalite sells their factory rifle for and we use many of their high quality parts. Except of course the parts we make that make these rifles really shoot. Accuracy Systems, Inc. has developed a conversion for the AR-10 Match Grade rifle to operate with the highly efficient and accuracy of the 300 Winchester Short Magnum cartridges. After comprehensive testing this combination of rifle and cartridge seem "made for each other". Use of the 300 WSM in the AR-10 increases velocity, energy, flattens trajectory a significant amount over the 308 auto rifle for the long range shooter. Functioning of the Winchester ammunition in the AR-10 is flawless and accuracy is usually under 1" MOA with factory ammunition, with some ammunition giving a three shot group of 1/2 MOA. Units for the 270 and 7MM have been developed. Other calibers based on the 308 Winchester case are also available. A.S.I. also has a wide variety of custom calibers for the AR-10. AR-10 Upper units and complete firearms are available from Accuracy Systems, Inc.


Here are a few available calibers we offer for the AR 10 conversions.

243 Win, 260Rem, 7mm-08, 284Win, 308Win "Match", 35Rem, 300Savage, 257Roberts, 358Win. 270WSM, 7mmWSM, 300WSM, 325WSM, 338WSM, 450Marlin and more!

Joe

What changes does he make to handle the .300 WSSM?

Ah yes the 30WSSM. .308 Win performance from an AR-15 platform. Oly calls it the .300 Olympic Short Magnum. Page 8 of thier 2006 catalog said the gun and it's ammo was supposed to be out already. I don't see it mentioned in the 2007 catalog, uh oh, maybe someone else can find it.

I havn't read anything from DTECH about it.

No AR10 platform...this is a mental exercise in expanding the capability of the 6.5 Grendel on the AR15 platform. Sounds like Oly could make a 6.5 Grendel magnum based on their other magnum rifles on the AR15 platform (same 6.5 Grendel cartridge but capable of handling higher pressure loads).

About 2 years ago, Lane Pearce ( Reloading Editor SGN) created a 6.5 RSUM. I think he called it the .264 Rocket. It was a 7mm RSUM necked down to the 6.5 caliber.

It was a real screamer. But in the real world...not even a blip on the radar.

These are fun distractions but thats all they are. We can argue over bolt's, brass and who's who. The real truth is that if we don't start working together, the AR platforms may be banned again within 3 years. There are not enough of us to support our own industry much less be a political factor in any election.

How long will it be before Illinois is AR Free? They lost all 5 seats in the Legislature last month.

We need to get more people shooting to defend our sport. Take a kid out with a 22.

Rant Off! Sorry!

John

Well with Martys new bolt, over at MGI, which I call the heavy metal bolt, a whole new realm of high velocity higher pressure rounds may be feasible on the AR15 platform. Only time will tell.

Joe

Well with Martys new bolt, over at MGI, which I call the heavy metal bolt, a whole new realm of high velocity higher pressure rounds may be feasible on the AR15 platform. Only time will tell.

Joe

What about an SR-25 bolt that has been redesigned for the Grendel? There would probably be some licensing fees from KA involved, but I bet it would be superior to the old design.

Ah yes the 30WSSM. .308 Win performance from an AR-15 platform. Oly calls it the .300 Olympic Short Magnum. Page 8 of thier 2006 catalog said the gun and it's ammo was supposed to be out already. I don't see it mentioned in the 2007 catalog, uh oh, maybe someone else can find it.

I havn't read anything from DTECH about it.



Damn, I have been wishing I could build one of those. I never saw their version, I still think a .30 WSSM would be good. I would think it would actually be closer to .30-06 performance, based on the performance of the .25 WSSM.

IIRC, he will not build 6.5WSSM because it has not been certified by Olympic Arms.

In addition to Oly barrels DTEC also sells Shilen barrels chambered in, among many others, 6.5 WSSM, 7 WSSM, 300 WSSM, 338 WSSM, and 358WSSM. :D

The WSSM case is 1.670 long so the longer 6.5mm ogive bullets are out. :(

I find myself getting caught up in this kind of thinking all the time. In the end it seems rather futile.

Trying to reinvent the wheel? WHY? :confused:

I find myself getting caught up in this kind of thinking all the time. In the end it seems rather futile.

Trying to reinvent the wheel? WHY? :confused:

I don't think it would be futile at all. Change the locking lugs and the extension lugs to the "rounded" shape based on the SR-25 bolt, and perhaps the Grendel could surpass the 308.


ok ok that's just wishful thinking and I'm not an engineer :)

The 6.5mm Grendel already surpasses the .308 WINCHESTER. It stays supersonic past 1,000 yards. Or so they claim. Has less drift.

I've been wildcatting a while. I think other than a little tweaking on the case for no trimming, that you will get any more out of the AR platform due to the pressure limits. The wildcat reamer I'm having made changes the shoulder angle to 35 degrees, it will give added capacity for powder. This will become useless space. Tighter dimension for the chamber will maybe pick-up a little more accuracy?

Now that I have this Les Baer upper with the 26" barrel chambered for the 6.5 Grendel, I'll know what if anything I've gained for all the money I'll be spending wildcatting the Grendel.

The 6.5mm Grendel already surpasses the .308 WINCHESTER. It stays supersonic past 1,000 yards. Or so they claim. Has less drift.

I've been wildcatting a while. I think other than a little tweaking on the case for no trimming, that you will get any more out of the AR platform due to the pressure limits. The wildcat reamer I'm having made changes the shoulder angle to 35 degrees, it will give added capacity for powder. This will become useless space. Tighter dimension for the chamber will maybe pick-up a little more accuracy?

Now that I have this Les Baer upper with the 26" barrel chambered for the 6.5 Grendel, I'll know what if anything I've gained for all the money I'll be spending wildcatting the Grendel.

The bolt is the weak link. There's a fellow that goes by the name Constructor that has modified some special bolts and has gone far past the 6.5 Grendel's velocities that are obtainable with the normal 6.5 Grendels out there. Another catch 22 is when you make the bolt stronger, then the extension lugs suffer, so those too would eventually have to be modified with a better alloy. If you want to really push the 6.5 Grendel you have to do it in a bolt action type rifle or if you prefer an AR type, then use an AR10 which to me defeats the purpose.

Joe

Thank you Joe. That was my point about going beyond what you have now, the pay back is what? That's why I wrote about the limitations of the AR platform. The pay backs are what after a certain point?

More velocity, for what? I want more, then I step away from the Grendel and go to other 6.5mm ctgs. They get me where I need to go. I just don't feel that I need more than 2500 fps for the 130 grain bullets. I think with my long barrels, I'll be able to do that with the Grendel. This is for caribou, they are not hard to kill. It's the darn wind that's the problem. Other wise the .223 Remington kills just fine.(if the wind doesn't blow you into the next country.

It's because, when we do this type of hunting it's better to have lots of follow-up shots. Lots of targets and a bag limit of 6 each makes for fast shooting. :D

In addition to Oly barrels DTEC also sells Shilen barrels chambered in, among many others, 6.5 WSSM, 7 WSSM, 300 WSSM, 338 WSSM, and 358WSSM. :D

The WSSM case is 1.670 long so the longer 6.5mm ogive bullets are out. :(
This is exactly why I was considering pushing the shoulder back on the WSSM to Grendel length, it would yield slightly more velocity and give the ability to use the longer target bullets. But the more I played around with the idea, the more it seemed that the velocity gain would not be enough to warrant the project. From what I can tell, the velocity gain would be no more than 200fps, not bad, but not great either. Seems to me that to develop a wildcat Grendel Magnum I'd want to pick up 300 to 400fps in velocity.

The 6.5mm Grendel already surpasses the .308 WINCHESTER. It stays supersonic past 1,000 yards. Or so they claim. Has less drift.


Depends on the bullet. Look at the Grendel vs the 308 with a 155 lapua scenar, rather than the M80 ball that AA uses for comparison.

The problem I see with a Grendel magnum is that you just end up recreating already proven 6.5 rounds. If you have to use an AR-10 platform, why not just go to 260 or 6.5x47?