6.5 Grendel Preferred Loads

[Grendel-Gene]

Grendel-Gene,
The extra 0.5 gr of 8208 gave me about at 30 fps increase with the 120 NBT. You should be close to 2500 fps with 28gr and your 18" barrel

Best,
PA

Maybe its wrong headed.... but I sure do like round numbers: 28 grains and 2500 fps.... sounds perfect! ha ha !!! Thanks PA!!! I will start loading up my Lapua brass as soon as i get the right shell holder for my Lee hand priming tool!!!

[Dacapster]

Here in AZ the 8208 XBR is crazy hot and only hits 2580-2680 FPS and destroys brass like litmus paper....

[Bwild97]

Here in AZ the 8208 XBR is crazy hot and only hits 2580-2680 FPS and destroys brass like litmus paper....

Are you using a 24" barrel? Because I have the same issues with 8208XBR. My theory is that XBR is just a little too fast burning for the long barrels

[Dacapster]

24 AA barrel yep!

[stokesrj]

This could be an important finding. I mostly shoot 8208 out of a 14.5" barrel 6.5 Grendel AR and a 24" bolt rifle that can withstand ye gads presure beyond bolt shear in a AR. However, the one pice of inconsitent information, my bolt rifle is not hard on brass. I get 16-20 loadings per case. There must be another factor in play here.
Bob

[LRRPF52]

It's the gas system. 8208 XBR has a pressure curve that can spike the gas system in a long barrel gun with the extra dwell time. Bwaites has no issues with one load in his 20", then the same load cranks out belted magnum Grendel brass from his 28".

[Bwild97]

Dacapster, Have you fired any factory loaded Hornady through your rifle yet? I get the same from factory loaded 123g Amax.

[blackfoot]

I'm seeing good results with 8208 and 123 Scenar in a 24" tube. I'm beating factory AMax velocities and no signs of excess pressure. It's a 24" Les Bear .264 LBC.

[kegs]

Well this is a heck of a thread & a good idea. I've been wanting in the Grendel horde for a couple of years now, already set up for reloading, have a range here on my land & also have a chronograph. I now have a gun (20" bbl - though this is the "sporter chamber" - which may have different results than the Grendel - we shall see. I'm just waiting for some mags & dies from AA. I will jump into this game as soon as I am fully up & running. I have a bunch of Hornady 123A's coming, so I figure I'll burn through a few rounds first to get some brass to load up, then get the powder/primers/brass. I am probably only going to start out with a couple of powders, but I will make note of the loads noted on here and use those first to see how they do in my gun...

[bwaites]

It's the gas system. 8208 XBR has a pressure curve that can spike the gas system in a long barrel gun with the extra dwell time. Bwaites has no issues with one load in his 20", then the same load cranks out belted magnum Grendel brass from his 28".

This is exactly correct, LRRPF52 has an incredible memory! I can crank out 123's all day with my 20" and the XBR 8208 loads at 27.5-28.5 and have no issues. That same load in my 28" makes it one shot brass. You cannot resize Grendel belted magnum brass!




The most significant thing I've confirmed with this is that looking at primers is mostly useless in AR's, because these primers look pristine, there is no ejector swipe or other sign of pressure on the base either. The case just becomes belted. I threw away about 60 pieces of brass while developing loads. Fortunately, it all had more than 10 reloads on it, but it still hurt my heart! LOL!!!

[stokesrj]

Yes,
If you are using the correct thick walled primers they will not show the pressure signs until it is too late and you are ruining brass. If on the other hand you are using thin walled primers, they will show the high pressure signs well in advance of max. However, they will not allow you to reach max pressures. So, In my opinon use only thick walled primers and pay special attention to brass flow into the extractor recesses and ejector pin. These will allow you to reasonably assess when you are approaching max pressures.

I still don't get the 24" thing though, my Panda Stolle which also has a 24" barrel will handle loads until the brass is a one shot affair.

Bob

[bwaites]

Yes,
If you are using the correct thick walled primers they will not show the pressure signs until it is too late and you are ruining brass. If on the other hand you are using thin walled primers, they will show the high pressure signs well in advance of max. However, they will not allow you to reach max pressures. So, In my opinon use only thick walled primers and pay special attention to brass flow into the extractor recesses and ejector pin. These will allow you to reasonably assess when you are approaching max pressures.

I still don't get the 24" thing though, my Panda Stolle which also has a 24" barrel will handle loads until the brass is a one shot affair.

So far, I've only use CCI 450's (and some Wolf SRM's in development).

After lots of back and forth with Bill Alexander and LRRPF52 and others, we think that the rifle length gas systems on the 28" rifles, and possibly on the 24" barrels (depending on how large the port is), allow the pressure spike of 8208 to start the bolt unlocking and the BCG to start opening before the pressure has dropped significantly enough to protect the brass.

In my 28", I go from no brass deformation or pressure signs to unusable brass with 123 grain bullets VERY quickly. 28.5 grains is too much with the 28", while it works very well in the 20". I realize my 28" is an outlier, since there aren't many 28" barrels out there. I don't generally base any load recommendations on the 28" data. 28.3 grains is slightly more accurate in the 20", so thats what I use. (I doubted I could actually tell a difference in .2 grains, but I can when shooting groups.)

I'm working on loads with CFE for the 28", and so far they show great promise. I'm up to 31.5 grains without any brass issues, no pressure signs, and improving accuracy still. Weather has been pretty wet to shoot at my development range, so I haven't been out lately.

My 20" is getting a cosmetic upgrade, so I haven't shot it in 3 months. I've got my fingers crossed that I get it sometime before Boomershoot in the spring, but I know life is very busy for my Cerakote guy, so I'm trying to be patient.

[bwaites]

All of the above said, my best load in this rifle at 600 yards is the 107 Sierra over 28.5 grains of XBR. Tiny groups at 100, and good out to 600. Since my plan was to shoot the Grendel at 600 in F Open and save my 7mm WSM for 800-1000 yards, I'm happy with that.

Bill

[Dacapster]

The only factory ammo I have tried was the wolf and even with them I get flat primmers. I will try the Hornady shells shortly. I will see if The CFE will be a bit better..

This was about the 4th reload on lee dies. AA brass. I will dial my gas block back to zero for the next few runs.

[Grendel-Gene]

After all my back and forth reading around here on this topic, I have decided to reload with the 123 Amax ( since it was designed for the Grendel chamber -as i understand it-, plus the 123 is in the right weight range for the twist rate in my 18" Satern Barrel - ); I have also decided to use the 8208 XBR powder, but be a bit conservative and just go 28 grains (instead of the 28.5 that many here have suggested ) because I have read here that you can go "over the edge" very quickly on XBR... so i will be on "the cautious side" and also be a bit kinder to my brass in the process. Speaking of brass, I will be using Lapua; I have seated my bullets to the "standard" 2.250 COAL. So, I will let you all know how it turns out. I already have reloaded 50 of these rounds this evening... Wish me luck: I am hoping this will become my "standard Grendel load" since i am inclined to find one thing that works fairly well, adopt it, and not change it anymore. Thanks fellas!!!