Sierra has posted data on the 6.5 Grendel online.   With 85 grain SV using Benchmark start load 26.9 max load 30.0 C.O.A.L. 2.120” with Winchestef Small rifle.   I always use primers with thicker cups to resist slam fires in the AR-15, normally CCI 41 or magnum CCI450.

With the 95 grain V-Max Benchmark start load 24.7 max load 29.4 grains C.O.A.L.  2.245”.   Hornady list the same powder data for the 95 grain V-Max, 100 grain A-Max and 100 grain soft point in my manual.

https://sierrabulletsblog.com/2017/11/16/sierra-bullets-6-5-grendel-load-data/

Thanks for the info and the link. Looks like benchmark is middle of the road for producing speed with the lighter bullets. Speed and temp stable is probably more important to us than absolute accuracy because we are shooting with thermal which can be a little less precise at times it seems. Speed matters due to trajectory and guessing ranges in the dark. The fastest load that will do around MOA is what we are looking for. I'll do a little research on the temp stability of those faster powders.

Looks like Benchmark does pretty well with the sierra 100 gr so it might still be a good choice for the 95 gr vmax. TAC seems to excel with both also.

I’ve used TAC with 95 grain V-Max and got good accuracy out of my 16” 6.5 Grendel.   There was an post on Accurate Shooter IIRC discussing temperature stability and stated the amount of velocity loss per degree.   I saved the post but can’t verify the source but the data seems worth considering.   The temperature stability listed for Benchmark is where I got my information.   I’ll post the information here and you can decide for yourself.

“20 degree temp change won't move impact a mil at 1000.  Look at the temps below for changes per degree. The most is 1.71 per degree. Using that and 20 degrees it comes out to about 34 degree change. Running my data on JBM, which I know is good, my load at 2895fps with the 140 AMAX is 7.9 mils at 50 degrees at 1000 yards. When I go up to 100 degrees it changes it to 7.6 mils. I have shot the H4350 loads from the teens to over 100 degrees with minimal chrono'd data shift.  Might be a tenth or two at 1000. That is from the ammo being in those conditions. Granted that is with H4350 and not the new powders being used but even if they were more there still wouldn't be a full mil shift.

HS-6 1.21fps per *
H110/W296 1.24 fps per *
Imr4227 1.17fps per *
Lil' Gun 1.31 fps per *
RL10x .71 fps per*
Benchmark .44 fps per *
Imr3031 .73 fps per *
Imr8208xbr .59 fps per *
H4895 .23 fps per *
Alliant Varmint pro .89 fps per *
Alliant AR comp .77 fps per *
Varget .19 fps per *
W748 1.32 fps per *
Imr4064 .53 fps per *
Ramshot Tac .91 fps per *
Imr4895 .87 fps per *
AA4064 1.11 fps per *
AA2520 .98 fps per *
RL15 1.52 fps per * from 50* and up
PP2000MR .99 fps per *
Imr4320 1.32 fps per *
Ramshot Biggame .98 fps per *
H380 1.44 fps per *
VV N150 1.08 fps per *
H414/W760 1.42 fps per *
Imr4350 .64 fps per *
AA4350 .47 fps per *
H4350 .29 fps per *
RL17 1.42 fps per *
Hybrid 100v .78 fps per *
RL19 1.61 fps per *
VV N160 1.24 fps per *
Imr4831 1.19 fps per *
Ramshot Hunter .86 fps per *
H4831 .36 fps per *
RL22 1.71 fps per *
Imr7828 1.36 fps per *
Magpro 1.01 fps per *
H1000 .21 fps per *
RL25 1.59 fps per *
Ramshot Magnum .87 fps per *
Retumbo .49 fps per *
RL33, still trying to get my data for this one.
US869 1.68 fps per *
H50bmg 1.64 fps per *.   “

That chart is great if it is accurate, I will print it out. For one thing it shows me that temp stability isn't as big a deal as I had thought. For example Tac is significantly more sensitive but even with a 75* temp swing it only amounts to an additional 35 fps loss, which is probably not significant for the ranges we will be shooting (especially with thermal) and would still probably be faster than Benchmark even with the extra loss.

Sorry for the side track here, I know this isn't the reloading forum but I doubt many there shoot lighter bullets out of 12" barrels.

I started with and have been using the Hornady New Dimension™ dies, but I'm looking at the Redding dies now.

There's a guy that does a lot of coyote hunting but with a 20" Grendel shooting 95gr V-MAX.

Shooting steel with my 12", the last time I was out, I never missed a mini steel buffalo silhouette at 450yds, and I was just shooting magazine monopod with this little 1-4x on it using Hornady 123gr American Gunner.  I think I was 10/10 hits on it...boring.

I really need to do video on it up there at the range, because people might have a hard time believing what is actually possible with such a small AR15 pistol.

I have a Redding 3 piece deluxe die set for my .223 reloading and I really like them. I would like to get them for the 6.5 but they seem to be about triple the price of the Hornadys.
Since you wrote the book on 6.5 reloading, do you think Benchmark or TAC are good light bullet powders or would you recommend something else in a 12" barrel? These will all be suppressed so I would guess we would want a fast powder to burn as much as possible in that 12".

It does make sense with a CLGS and suppressor to hit the port with the least amount of pressure, but still enough to cycle the action, which isn't a problem with the right port.

Benchmark was one of the early go-to powders for lightweight bullets in 6.5 Grendel.

H335 is another one.  Hodgdon's fastest mv with 90gr TNT was with H335.

Also 8208XBR.  8208XBR under the 95gr V-MAX will give you a lot of speed, as will H335.

If I was chasing speed with a faster burning powder under a 95gr V-MAX, I would probably do 8208XBR.

Once I get setup, I'm going to workup some loads using TAC.  Since this is what I use for 5.56, I won't need to stock separate powders.

So I'm looking at the Sierra link previously provided, under their 100gr HP, they show that H335 and 8208 are both considerably slower than both Benchmark and TAC. But they had a 24" test barrel. Does cutting the barrel length in half sort of rearange the order of velocity produced?
I've reloaded a fair while but not really gotten into the nuances of it so I'm just trying to understand it.
Thanks

I'm looking at Hodgdon's data in Volume II of the Grendel Reloading Handbooks, which you can also see on Hodgdon's site.

Velocity differences have more to do with powder lots I think.  Nitrating tree pulp is a hard business to maintain consistency with, which is why there is so much lot testing per SAAMI with ammunition manufacturing.

As customers, we think product X in a bottle will be exactly like that same product we bought a few years ago, but there are differences in major lots, hence the old reloading rule to always work up a new load when you switch to a new keg.

We've seen that with CFE223 recently, where the lots from 2-3 years ago were slower-burning than some of the more current lots on the shelves.

My 31.2gr load that was very well-behaved before now induces so much bolt bounce, that I can feel it on 18" MLGS Grendel, so the charge weight to achieve the same speed is noticeable lower and more around 30.0gr.

That's why I buy the 8lb kegs if I really find a powder I like.

This is a great thread. Unfortunately, it's going to wind up costing me $1,000.

Welcome to the club, though I got away a little cheaper having spare parts on hand... But on second thought, I *am* thinking of building another 6.5G upper... sooooooooooooo

So I have been reading this thread over and over again. I am unsure if I am going to be making a 6.5 pistol.  I am really interested though. I have a lower and upper sitting around was thinking of making it a 300 Blk, but when I im'd you and started reading this it changed.  Did you put a 2 stage trigger in it, is the shorted barrel 12.5 if it's going to get suppressed? Also where is the best place to find a barrel?

I'm doing a 12" SBR at the moment.  Ordered the Geiselle ACH and SD-E for it on black Friday.  The suppressor (Rugged Micro 30) for it is already in NFA jail as well.

Faxon and Ballistic Advantage are two of the more popular barrel providers.  I went BA for my 18" Grendel.  I just bought a cheap PSA 12" upper for this build, with a better barrel as the plan down the road.  Hard to pass up an mlok rail, BCG with 6.5G bolt, and an adjustable gas block for the ~$350 I paid for it.  So I now have a stripped upper I bought for this build just sitting around.

Yes, I have the LaRue MBT-2S trigger in it.

Barrels are available from:

Alexander Arms (11")
Ballistic Advantage 12.5"
Faxon
Grendel Forum Group Buy
Odin Works 12.5" Ultralite
Palmetto State Armory
Precision Firearms

What kind of results are folks getting with the Monster 12" barrels?