6x6.8 and/or 6 DTI Load Data

[TXCOONDOG]

I have a CH4D 6x6.8 dies and a 20" BHW barrel (P3) w/ 10T coming and need some info to get me going.

I like the Extreme Powders and have Varget , H322 & H4198
Primers: CCI 41 and various Bench Rest Primers too

I assume the same case length as 6.8 SPC which is: Min 1.676" Max 1.686" (I will cast my chamber).

These are the bullets I'm going to start with 55 Nosler, 58 V-Max and 65 V-Max

Note: Feel free and list any combos you have used with success in a 10 twist


Disclaimer: Any information posted by me is meant as information and may not work and be unsafe in your rifle/barrel. Therefore; If you decide to use the information provided then you are doing so at your own risk.

 

[Kino M]

Who's barrel and chamber/reamer?

 

[TXCOONDOG]

It's a BHW Barrel and I added that information in the original post.

I did some case comparisons (water weight in grains) and decided to start a grain below (just to be safe) the top 6 PPC load data and slowly working my way up until I get to 3400-3500 and/or see some type of pressure signs (primer flatting/cratering, swipes, burrs, etc.) with the 58 V-Max, H322 and BR4, Fed 205 and CCI 450 primers. The bullet touches the lands @ 2.245" so will start with a 2.230" C.O.L.

Case Length: Min 1.676" Max 1.686" (Target trim 1.680" + or - .001").

Note: I have about 400 pieces of once fired Hornady 6.8 SPC Brass that was annealed and sized to 6x6.8 SPC in a single step using the CH4D die.

Disclaimer: Any data posted is meant as information ONLY; may not work and be unsafe in your rifle/barrel. Therefore, if you decide to use the information provided, then you are doing so at your own risk.


Here's the 6x6.8 SPC with TI Can, Texas Predator Posse Edition Lower with Timney 3lbs trigger and Thermion XP 50 Pro 2-16 Thermal

Waiting on the adjustable gas block and Acra rail but thought I would post how the build is coming.

 

[TXCOONDOG]

Went to the gun range this morning testing H322. I decided to try different primers at the same charges to see if there was a difference in velocities and pressure signs.

Note: This was just to establish a baseline and didn’t test for accuracy. I started one grain below the max 6 PPC data for my starting point.

Caliber: 6x6.8 SPC
AR 15 Barrel: 20” BHW (P3) with 1:10 Twist
Brass: Hornady 6.8 SPC once fired brass and necked/sized down to 6mm
Brass trimmed to: 1.680”
Primers: See Below with charge weights and velocities
Bullet: 58 Gr V-Max
COL: 2.230”


Date: 4/30/2024
Weather: Clear Skies @ 70 degrees, Humidity 65% with 2 MPH Wind
Chronograph Used: Garmin Xero C1


Disclaimer: Any information posted by me is meant as information and may not work and be unsafe in your rifle/barrel. Therefore; If you decide to use the information provided then you are doing so at your own risk!!!!!

A 10" drop tube was used in order to get the powder below the neck of the case starting at 29.5 grains.

CCI BR4 Primers and H322 Powder

28 Gr = No Reading
28.5 Gr = 3178 FPS
29 Gr = 3273 FPS
29.5 Gr = 3324 FPS
30 Gr = 3390 FPS
30.5 Gr = 3519 FPS Light Ejector Mark
31 Gr = 3541 FPS Heavy Ejector Mark

CCI 450 Primers and H322 Powder

28 Gr = 3167 FPS
28.5 Gr = 3256 FPS
29 Gr = 3231 FPS
29.5 Gr = 3300 FPS
30 Gr = 3347 FPS
30.5 Gr = 3412 FPS Light Swipe
31 Gr = 3501 FPS Ejector Mark

Federal 205 Primers and H322 Powder

28 Gr = 3143 FPS
28.5 Gr = 3217 FPS
29 Gr = 3255 FPS
29.5 Gr = 3374 FPS
30 Gr = 3373 FPS Starting to see swipes
30.5 Gr = 3397 FPS Light Ejector Mark
31 Gr = 3466 FPS Ejector Mark


I’m currently working on some loads using 55-70 gr bullets in two (2) different AR 10's in 243 so it could be a while before I start posting any group size testing, etc.

 

[TXCOONDOG]

My AR 10 243 loads have been worked out so I'm ready to start my load and accuracy testing with the 6x6.8.

 

[TXCOONDOG]

After making some tweaks to the gas system (no more ejector marks) and shooting between 50-300 yds, this load end up being the most consistent (repeatable)
CCI 450 Primers and H322 Powder 31 Gr = 3522 FPS (20 shot avg with an SD of 6.3)

Here's a pic of the setup for my grandson with a Sightmark Wraith Mini Thermal, Ti can and sitting in a FATBOY tripod.

 

[dozer_xj]

Its been a few years since I I had a 6x6.8 but I remember we used h322 for 58s, arcomp for 70s and 75s. 8208xbr was accurate but slower. I had a 58 grain load with h4198 that shot good too with decent speed. It mis mid 20 grain range.

 

[NCroark]

After making some tweaks to the gas system (no more ejector marks) and shooting between 50-300 yds, this load end up being the most consistent (repeatable)
CCI 450 Primers and H322 Powder 31 Gr = 3522 FPS (20 shot avg with an SD of 6.3)

Here's a pic of the setup for my grandson with a Sightmark Wraith Mini Thermal, Ti can and sitting in a FATBOY tripod.

After making some tweaks to the gas system (no more ejector marks) and shooting between 50-300 yds, this load end up being the most consistent (repeatable)
CCI 450 Primers and H322 Powder 31 Gr = 3522 FPS (20 shot avg with an SD of 6.3)

Here's a pic of the setup for my grandson with a Sightmark Wraith Mini Thermal, Ti can and sitting in a FATBOY tripod.

Sure would love to get more 322 for my 6x6.8. Hodgdon says it's coming soon but I'll believe it when I see it. 31gr is where mine shoots best, right at 3600. I've tried to duplicate it with 10x but not quite there, the 322 is pretty accurate

 

[Coyote-conquest]

I know you said you like the extreme powders but you'll get a lot more speed with ball powders. I use Lever with 70 gr BTs. I've also used a lot of BLC2.
I've used a lot of Xterminator and H335 for the 55s.
Extruded powder will work but it will most likely be little slower.
Load data for the 6arc I think is fairly similar.

 

[DeereGreen]

I know you said you like the extreme powders but you'll get a lot more speed with ball powders. I use Lever with 70 gr BTs. I've also used a lot of BLC2.
I've used a lot of Xterminator and H335 for the 55s.
Extruded powder will work but it will most likely be little slower.
Load data for the 6arc I think is fairly similar.

Usually just the price your willing to pay for temperature stability.

 

[flowj]

A lot of info here. I tested H322, XBR, and AA2200 in my 6X6.8. I settled on 30.9 XBR, 41 primer, 58Vmax in Hornady brass. I get 3371 fps and no brass beatings. The gun shot well with all 3 powders and can make a lot more speed but was beating up brass. Adjustable gas block helped but when I went suppressed I can't dump enough gas to get back where I need to be. I probably need to move the AGB and block some of the gas hole for more control, but the gun does what I need it to do. I was shocked at the difference between the 6X6.8 and a .223 on coyotes. I did make note in my testing that 41 primers made about 50 fps more than 400's and 450's made about 20 fps more than 41's across the board. Also found a big difference in max loading between Hornady brass and old stock SSA. Never measured the capacity but there is a difference so if you load the wagon and change brass back off, or you'll be auto ejecting primers!

 

[Jerryrigged]

Also watching this thread, have a 6DTI on the way. But I am going to start out with the 75 Vmax, see how those work. Bulk of my shooting is 150-250 yd, but the occasional 400+ shot presents itself.