Real world 6.8 SPC II Data

Catdog1

New member
What kind of honest velocity can i expect out of a 16" barrel compared to advertised numbers. Mainly 90-110gr. bullet weights.

Hogdon data shows 3049fps with a 24" using cfe black with 90gr bullet. Is this something that is probably true?
 
Last edited:
Originally Posted By: Yote chaserim shooting a 95ttsx out of a 16in bison barrel right at 2700 fps thank u for the info.
 
With my 16" barrels, I'm getting 2800 FPS with my handloaded 90 gr Speer Gold Dots. 110 gr Sierra Pro Hunters and Hornady V-Max handloads are clocking 2566 FPS. These loads were measured through my chronograph @ 12' from the muzzle.
 
I have a 18" ARP barrel(1:11.25" 5R) that chronographs 95 gr. Barnes TTSX loads at 2850 FPS, with no signs of pressure.

Real world speeds will have more to do with the barrel twist rate, and of course quality, than length of barrel. The early standard barrel twist rate for the 6.8 SPC was 1:10, which was an artifact from the 270 Win. chambered rifles. So enterprising 6.8 fans started playing with barrel twist rates, and found they could use slower rates, like 1:11-1:12, to get better velocities, before signs of pressure showed up, using fairly fast powders. So "real world velocities", in any barrel, will only be a fair comparison, if one adds twist rate of the barrel, to the comparison.

As an example, I have a 6.8 SPC II RRA upper(16" barrel 1:10" twist), that when tested with the same 95 gr. Barnes TTSX loads, showed signs of pressure, so I didn't even chonograph them, as I will have to adjust the load, for this rifle. It is relegated to Home Defense/yard varmints duty, so I have 110 gr. VMax load that is developed for this rifle, and IIRC it chronies around 2600 FPS.

Squeeze
 
Originally Posted By: SqueezeI have a 18" ARP barrel(1:11.25" 5R) that chronographs 95 gr. Barnes TTSX loads at 2850 FPS, with no signs of pressure.

Real world speeds will have more to do with the barrel twist rate, and of course quality, than length of barrel. The early standard barrel twist rate for the 6.8 SPC was 1:10, which was an artifact from the 270 Win. chambered rifles. So enterprising 6.8 fans started playing with barrel twist rates, and found they could use slower rates, like 1:11-1:12, to get better velocities, before signs of pressure showed up, using fairly fast powders. So "real world velocities", in any barrel, will only be a fair comparison, if one adds twist rate of the barrel, to the comparison.

As an example, I have a 6.8 SPC II RRA upper(16" barrel 1:10" twist), that when tested with the same 95 gr. Barnes TTSX loads, showed signs of pressure, so I didn't even chonograph them, as I will have to adjust the load, for this rifle. It is relegated to Home Defense/yard varmints duty, so I have 110 gr. VMax load that is developed for this rifle, and IIRC it chronies around 2600 FPS.

Squeeze i appreciate the info.
 
I thought this was the real world?

Anyways with Cavity Back Bullets 105gr MKZ I'm getting 2740fps on a 83* day from a 16" Wilson Combat lightweight barrel and SDN6 suppressor. My load is 29gr of AA2200 at 2.295" OAL, cci#450 primer. Be safe, work up.

As far as factory ammo:
Federal XM68GD 90gr Gold Dot, 2884fps, 91* day
Hornady 110gr V-max, 2659fps, 92* day
Hornady 110gr V-max, 2591, 46* day
Hornady 110gr V-max, 2615, 51* day (16" Ar Performance barrel, SDN6 suppressor)


And just for fun a 20 Tactical:
Hornady 32gr V-max, 4155fps, 55* day (handload, overmax)
 
All i have in my notes on my phone is this.

6.8
ARP 12.5"
AA2200
CCI400
85gr Barnes TSX

30.0 2618
30.5 2710
31 2733
31.5 2767
31.8 2798
32.0 Was very hot load. Settled on 31 grains.
 
Wormydog1724 that's smoking for those 105 grain MKZ's out of a 16 incher. I took a snapshot of you're load gonna try them in my 16 and 18 ARP. I also bout a box of the 120 grainers to try in my 270wsm. Lol I've gotta feeling those are gonna be devastating.
 
CFE-BLK is even faster! That stuff is impressive! The groups weren't the best but I'm taking full responsibility on that. I have a feeling they are better than I produced.

............................................fps. ............std.............group
New MKZ 27.8gr CFE-BLK..........2774..........27.6............ 1.23"
New MKZ 28.1gr CFE-BLK..........2790..........35.7............. 3" (not a good rep of accuracy here, my fault)
New MKZ 28.4gr CFE-BLK..........2840..........12.1............. 2" (I don't think this one is safe and wouldn't do it again)

I'm going to try right on 28gr and mess with the COAL a bit.
 
Originally Posted By: wormydog1724CFE-BLK is even faster! That stuff is impressive! The groups weren't the best but I'm taking full responsibility on that. I have a feeling they are better than I produced.

............................................fps. ............std.............group
New MKZ 27.8gr CFE-BLK..........2774..........27.6............ 1.23"
New MKZ 28.1gr CFE-BLK..........2790..........35.7............. 3" (not a good rep of accuracy here, my fault)
New MKZ 28.4gr CFE-BLK..........2840..........12.1............. 2" (I don't think this one is safe and wouldn't do it again)

I'm going to try right on 28gr and mess with the COAL a bit.

Ha look close at your group size. Looks like your saying they are 0.3" and 0.2"... Might want to move the periods/decimal place.

Well i refreshed the page and now it doesnt show it like that.. hum..
 
Last edited:
Gotcha. Let me know. I have several pounds of the 2200. I'm thinking I should be able to push the 120 grainers around 3400 with RL19 in my 270WSM just hope I can get the accuracy.
 
Originally Posted By: NonnieselmanOriginally Posted By: wormydog1724CFE-BLK is even faster! That stuff is impressive! The groups weren't the best but I'm taking full responsibility on that. I have a feeling they are better than I produced.

............................................fps. ............std.............group
New MKZ 27.8gr CFE-BLK..........2774..........27.6............ 1.23"
New MKZ 28.1gr CFE-BLK..........2790..........35.7............. 3" (not a good rep of accuracy here, my fault)
New MKZ 28.4gr CFE-BLK..........2840..........12.1............. 2" (I don't think this one is safe and wouldn't do it again)

I'm going to try right on 28gr and mess with the COAL a bit.

Ha look close at your group size. Looks like your saying they are 0.3" and 0.2"... Might want to move the periods/decimal place.

Well i refreshed the page and now it doesnt show it like that.. hum..

It's your eyes. You're getting old!
 
Originally Posted By: wormydog1724Originally Posted By: NonnieselmanOriginally Posted By: wormydog1724CFE-BLK is even faster! That stuff is impressive! The groups weren't the best but I'm taking full responsibility on that. I have a feeling they are better than I produced.

............................................fps. ............std.............group
New MKZ 27.8gr CFE-BLK..........2774..........27.6............ 1.23"
New MKZ 28.1gr CFE-BLK..........2790..........35.7............. 3" (not a good rep of accuracy here, my fault)
New MKZ 28.4gr CFE-BLK..........2840..........12.1............. 2" (I don't think this one is safe and wouldn't do it again)

I'm going to try right on 28gr and mess with the COAL a bit.

Ha look close at your group size. Looks like your saying they are 0.3" and 0.2"... Might want to move the periods/decimal place.

Well i refreshed the page and now it doesnt show it like that.. hum..

It's your eyes. You're getting old!

frown.gif

I blame it on lack of sleep....
 
I have a Bison Armory 16" Recon profile barrel on my 6.8 SPC II AR. I get 2780 FPS on my Chrono using RL 7 under 90 grain Speer TNT's with no signs of pressure. I believe I could push my loads harder but the rifle is very accurate at this velocity.
 
Last edited:

90gr TNT, Nosler case, CCI 400, AA2200
16" 11.25 twist ARP barrel.
28.5gr 2544fps
29gr 2560
29.5gr 2625
30gr 2684
31gr 2750 less than 1.25 inch @ 200 yards


110 vmax, Hornady case, CCI 400, AA2230
16" 11.25 twist ARP barrel 2520fps
16" 10 twist BHW barrel 2531fps

COAL 2.290" of all rounds
 
Last edited:
Originally Posted By: rustybucketNotes from my phone. I haven't chrono'd my final load of 31 grains...

AA2200
28.5gr 2544fps
29gr 2560
29.5gr 2625
30gr 2684

Current load is 31 grains of aa2200

What bullet, case, and primer?
 
Back
Top