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Discussion Starter · #1 ·
Just wanted to provide some chrono info in a new upper I recently built with these two loads.

Daniels Defense 16" 5R Cold Hammer Forged Chrome Lined S2W (heavy profile) SPC II Chamber (chamber is also chrome lined), this is a brand new 2020 production barrel with 1:11 twist, no the old 1:10.

110gr Hornady OTM (BTHP) American Gunner Factory:
7 Shot String #1
Average: 2,593 fps
Extreme Spread: 27 fps
Standard Deviation: 9 fps
Temperature: 70 F

110gr Hornady OTM (BTHP) American Gunner Factory:
7 Shot String #2
Average: 2,590 fps
Extreme Spread: 22 fps
Standard Deviation: 7 fps
Temperature: 70 F

110gr Nossler BTHP loaded by Druid Hill:
13 Shot String #1
Average: 2,663 fps
Extreme Spread: 67 fps
Standard Deviation: 19 fps
Temperature: 70 F

Note that I was having short stroking issues with Druid Hill's loads. I suspect they are using a faster burning powder that isn't generating the requisite port pressure that Hornady factory ammunition is, which is my default tuning load.

Buffer: JP SCS configured with the default 85% power spring (black, about equivalent to a GI spring), 1 tungsten and 2 steel weights (3.8oz) using a Low Mass (8.5oz) NiB bolt carrier. It's a hybrid setup, not quite low mass, but not as heavy as a standard carrier / carbine buffer setup. Absolutely love the recoil impulse of this config.

Gas Block: 8 clicks from fully closed out of 15 settings, just over 50% open.

This setup locks back every time on Hornady OTM and ejects around 3:30~4 but short strokes on the Druid Hill even with the gas block opened up to 100% (15 clicks). No signs of pressure issues with the cases on either load. Cases look insanely clean, in fact the cleanest brass I've ever seen come out of an AR.

I may try the weakest 80% buffer spring with Druid Hill to see if it will cycle and lock open consistently, otherwise it's a no-go load for my upper despite the excellent muzzle velocity.
 

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Maybe try closing the gas off on Druids . Possible that since velocity is higher so is gas pressure through block and it is trying to open bolt too early .

Sent from my LM-K920 using Tapatalk
 

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Discussion Starter · #3 · (Edited)
Maybe try closing the gas off on Druids . Possible that since velocity is higher so is gas pressure through block and it is trying to open bolt too early .

Sent from my LM-K920 using Tapatalk
I would expect to see signs of that on the cases however, such as a lot of powder on the cases (pulling them early, I'd expect a lot of gas leakage). I didn't see any signs of that, brass is clean as a whistle just like the Hornady. But I will give it a try next time.

I also have two different JP SCS buffer assemblies, since they are modular I can just pop them out with even less effort than swapping a standard buffer / spring, so it would take only a few seconds to try the weaker 80% white buffer spring, but I will keep that in mind as well for the druid hill.

Ideally if I could get it to cycle on the same gas setting as the Hornady, I'd rather just swap a buffer for that load than mess with turning the gas flow metering screw and counting clicks, but we'll see.

Velocity results are good however and slightly higher than what I was getting with my ARP 3R with DMR chamber on the Hornady. It's right in the sweet spot for velocity, accuracy and recoil. It cycles uber reliable which is why Hornady has become my go to tuning load for new builds in 6.8 SPC, then I test other loads from there.

Although I will say Wilson Combat's factory loads were also on par with Hornady's in terms of cyclical reliability and accuracy, they are just even more expensive and completely unobtainable currently (I've used their 95gr TTSX and 110gr TSX).
 

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This is my experience. DHA was using a fast proprietary powder that was somewhat workable with 90 GDs. I've shot the the 90 GDs in 12", 16", and 20" ARP barrels. I had failure to lock-back multiple times on the 12" and 16" mid-length gas while the rifle gas on the 20" had short stroke problems. I've also shot 105 and 120 grain bullets with this powder which was unsuitable. I've heard from an industry source that DHA is changing to slower powder but they are having component supply issues like the rest of us.
 
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Discussion Starter · #5 ·
Well that's not good to hear as I have quiet a bit of it. Once I get time to get back out, I'll report back on weather I can get it to cycle on a softer buffer spring. At least at that point I've tuned with all the options available, I may contact them regarding this if it's a no-dice situation no matter what, but you basically confirmed my theory. Thanks for the info Xman.
 

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Discussion Starter · #6 ·
This is my experience. DHA was using a fast proprietary powder that was somewhat workable with 90 GDs. I've shot the the 90 GDs in 12", 16", and 20" ARP barrels. I had failure to lock-back multiple times on the 12" and 16" mid-length gas while the rifle gas on the 20" had short stroke problems. I've also shot 105 and 120 grain bullets with this powder which was unsuitable. I've heard from an industry source that DHA is changing to slower powder but they are having component supply issues like the rest of us.
I ended up calling DHA and confirmed the burn rate issue. Great to work with and I was told that if I cant' get it to cycle he will exchange all of my 110gr Nossler for VMAX or SST loadings that will be available in about a month using a slower burning powder. So the last tool I have is a weaker buffer spring which I'm hesitant about regarding feed issues (some times the reduced powered springs won't reliably strip the next round from a fully loaded mag).

With the JP SCS I'm already running the black 85% power spring (second weakest in the pack of 5 springs), the only one weaker is the 80% white spring which is geared towards 5.56 competition guns running ultra lightweight aluminum carriers and shooting bunny farts at paper....I'm already running a lighter weight action than standard and have an SLR Sentry 7 adjustable gas block, so other than drilling the port larger which I'm NOT willing to do on an expensive chrome lined barrel, there's no where else to go.

It'll be a shame because the 110gr Nossler load from DHA is giving me great velocity out of the 16" 5R 1:11 Daniels Defense barrel.

On a side note, when I was testing my two new uppers (one 5.56 and one in 6.8, both Daniels barrels), both low mass NiB carriers I bought from FosTech were incorrectly assembled and leaking gas like crazy. In fact they were so bad I used a feeler gauge and found 0.003" gap between the carrier gas key and carrier!

So I used a hex key and just out of curiosity turn the "staked" screws and found they didn't torque them down. Apparently some one on the assembly line only threaded them in loosely then staked in the loose screws (this was all before testing the Druid Hill 110gr and if for reference only).

Other than the obvious issues of significant short stroking even with 110gr Hornady OTM factory load, one other sign I noticed was very low muzzle velocity. My average was around 2530 FPS instead of 2590 I got once I replaced the carrier keys on both carriers (torqued to 55 in-lbs, thread locked using Holokrome IP25 screws).

So if you have a Chrono, it might be a useful tool to once a year check your average velocity on a known good load as a test for leaks in the gas system. I was loosing 60 FPS from those leaks on the 6.8 upper, but not quite as much on the 5.56 upper (my guess because of the faster velocity, shorter dwell time and consequently less lossy).
 

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Glad you have a path forward. Sound like you have another update to provide us.
 

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Discussion Starter · #8 ·
So wanted to provide an update on the DHA 110gr Nossler load I've been having issues with. It's a no-go for my particular rifle application and requirements. The rifle did cycle just fine with the softer buffer spring, including locking open on the last round (tested seven one round mags in a row, locked back every time), however it has intermittent failure to feed on a fully loaded or near fully loaded mag. Solved one problem, created another (and I expected this would probably be the case as I had tried that buffer spring weight before way back when I first started and had that issue, but wanted to give it one more shot, pun intended).

The white 80% buffer spring for the JP SCS (similar to a reduced power buffer spring) is really intended for competition applications using very low mass BCG's on 5.56 uppers shooting bunny fart loads. I think the combination of a heavier cartridge (110gr vs. 55gr, larger case, more powder) in a fully loaded 25 round mag is just a bit too much resistance for such a soft spring with the given BCG / buffer mass. And I'm not inclined to be swapping buffer configs just to use a different load than my standard 110gr OTM.

So DHA is going to refund me for the ammo I bought (including the 25ish rounds I fired trying to trouble shoot). I think that load would work just fine for a hunting rifle if you kept it clean (mine was dirty with 300+ rounds through it and had not yet been re-lubed or cleaned), but for my applications I need a little more cyclical reliability for heavy fouling, high heat and low lube conditions.

Once they get some new loads worked up on powders that produce better port pressures on mid-length gas systems I'll give their ammo another try down the road as I was very pleased with the average velocity of 2663 FPS out of a 16" barrel.

For reference factory Hornady 110gr OTM this outing produced an average of 2584 FPS, 20 FPS Extreme Spread and only 6 FPS standard deviation (this load is UBER consistent), so DHA's loading is certainly hotter, but in this case compromised functional reliability in my upper which is already running a lower mass BCG (13.1oz total vs. 14oz for typical carbine setup).
 

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Discussion Starter · #9 · (Edited)
Just for reference, if anyone is interested in the comparison, I also got my 5.56 training upper going while finishing up testing of my 6.8 upper on various loads and have some interesting data.

Using 77gr Razor Core Mod1 (IMI), I netted an average of 2586 FPS from a 16" Daniels Defense Light Weight profile barrel (basically Gov profile at the back, but thinner up front). 6 grove, NATO chamber, 1:7 twist, mid-length gas, hammer forged and chrome lined.

My 6.8 SPC upper runs a Daniels Defense S2W profile, 1:11 twist, SPC II chamber, also mid-length, also hammer forged and chrome lined. Shooting my default tuning load of 110gr Hornady OTM factory ammo, I netted 2584 FPS average. Both of these were chronoed on the same day within about an hour apart.

Using Hornady's Ballistic Calculator to estimate drop and drift in MILs, they are nearly identical in trajectory out to 700 yards (well past their practical limits). IMI 77gr Razor Core Mod 1 is a high performance heavy OTM load intended for long range accuracy and optimal terminal performance in combat applications, but is not considered barrier blind. Both IMI 77gr 5.56 and Hornady 110gr OTM 6.8 were MOA or better accuracy (about the same) using a 1-6x LVPO and bipod off the ground fairly quickly as I was pressed for time, with a higher mag scope and more time, they would probably both be in the 1/2 to 3/4 MOA range.

The 5.56 upper uses a Vortex Viper PST Gen II 1-6x while the 6.8 SPC upper wears the more expensive Vortex Razor HD Gen II-E 1-6x. Both on Badger Ordnance C1 mounts at 1.70" height (aka lower 1/3). Both have the same Anderson forged mil-spec uppers (Cerro Forge if anyone cares), both are bedded and torqued to 55 ft-lbs. As mentioned, they are pretty much clones just with the caliber specific differences and some cost saving measures here or there on the 5.56 upper since it's mostly for training purposes.

While I don't in any way suggest 5.56 isn't lethal or usable, because it is, it is not OPTIMAL for it's application in my opinion (and extensive research on the limitations of 5.56) and I think the differences in terminal performance are quite significant at all usable ranges and I've really come to appreciate the 6.8 SPC cartridge and what it can achieve in a small frame AR relative to the native 5.56 cartridge.

And that's comparing hot NATO loads in 5.56 to more mundane SAAMI spec loads in 6.8 SPC, for which there is a decent amount of headroom still available to further increase performance in 6.8 SPC. 5.56 is pretty much tapped out at this point in terms of factory loads.

Load Reference Info:

IMI specs 77gr Razor Core at 2739 fps from a 1:7 20" barrel, so my results seem about right given 5.56 is much more fickle about barrel lengths than 6.8 SPC. This load was intended to provide increased lethality over M855 which as we know generally has poor terminal performance overall. MK262, MK318 and 62gr Bear Claw (federal's bonded soft point) are probably the three best 5.56 factory loads out there unless you go to uber expensive monolithics from Barnes etc.

Hornady specs 110gr OTM (American Gunner) at 2570 FPS for a 16" barrel. My results are right on the money. This is the final bullet Hornady originally came up with after their initial 115gr OTM that was used in the majority of development testing. Sadly is it no longer in production, however the V-Max bullet is a close proxy with a lower frag threshold than the older OTM (what they call BTHP), but for the price it was at, it's sad to see the OTM American Gunner line go as it's a good all around load and was literally one of the cheapest 6.8 factory loads out there (I got mine back when it was $0.59 a round on SG Ammo).
 
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