AR Comp loads running very slow

[Diesel Pro]

I bought a pound of AR Comp to work up for my 6ARC as well as 223/556.  Problem is, it's lacking velocity big time in both calibers. Not even close to what QL predicts. QL is pretty spot on with other powders that I have tried.  When I ran Comp in my 22" 6arc my speeds were in the 2300-2400 when predicted 2800+

Comparing Comp to 8208 in my 223 60gr NBT Rem 1-1/2 primer Springfield Saint Victor 16"  Outside temps low 40's

24.2 grains Comp nets 2479 average with ES of 117. QL predicts 2895 so 400 short  of prediction 

24.2 grains 8208 nets 2705 average with ES of 54.8  QL predicts 2760 only 55 short of prediction


Note: the 8208 3 round string had 2 of 3 within 1 fps of each other 2686.9 and 2687.9

About all I can think of is a bad lot or a bad bottle.  My 8208 is from an 8# jug that is well over 10 yrs old.

[SpeyRod]

That is very slow. I’m getting 2,300+ from factory 108’s in my 12” Arc.

What is listed max and fill %?

[Diesel Pro]

Alliant shows 223 data as follows 25.6gr 55SBK 24" barrel 3350FPS That's pretty compressed

Back off 50fps per inch (8x50=400) for my 16" barrel to 2950 expected

My actual observed with this load is 2768 with mediocre sd of 28.3

25.6gr of 8208xbr yields 2990 with sd of 3.9 and that is with a 5gr heavier bullet.

Not sure if anyone has ever drawn a direct comparison between comp and xbr but 230fps seems pretty significant and would be greater with same weight projectile. They aren't just too far apart in the burn rates. QL underestimates 8208 and overestimates my particular bottle of comp.

[grayfox]

DP your posts confuse me. The only bullet I see is a 60 gr Nosler in 223, and no pills in the 6 Arc. 556 and 6 Arc are going to be apples and oranges.

So since this is not a 556 forum, and no data to work with in 6 Arc, what gives??

And is the 6Arc a gas gun or bolt?
AR Comp is a derivative of RL-15, which is mentioned in Hornady data for 87 gr-105's... RL-15 not being the best powder in terms of MV... but when they tweaked RL15 into Ar comp it sped up in burn rate, so it is not 1 for 1.
I find Comp's best uses for me in the 6.5 grendel 120-class bullets, but again, the grendel needs a different powder burn rates due to being 6.5 vs 6mm (less bore cross section usually means slower burn rates needed). I also use it sometimes in 308 for my 110 ttsx, but note again this is a fast little bullet ... up-shot is you might find it too fast for the 6 Arc, so won't get enough powder charge in it to accelerate properly.

[Diesel Pro]

Apologies. I made contact with Alliant and since I was currently working with my 223/556 16" AR AND because the guy I talked to doesn't believe in QL, we used existing load data from their files. That and I wanted to see if the issue followed to a different cartridge and it sure seems to have.

I'm new to QL but have a pretty solid grasp. It has been remarkably close at predicting loads for LVR, 8208, etc but way off on Comp. I can't blame QL though as the numbers are just plain low compared to another contacts results.

I did a ladder with my 22" Cobalt Kinetics gas gun using Comp and 103 ELDX. The numbers show QL predictions first vs observed at top and bottom

23.8 2540 predicted vs 2120 observed
24 2557
24.2 2574
24.4 2591
24.6 2608
24.8 2625 QL says 53k 2286 observed
25 2642
25.2 2659 vs 2294fps observed
25.4 2676
25.6 2692 predicted vs 2320fps observed

Same gun, same 103ELDX with LVR including sd numbers Actual numbers first

LVR ladder CK

27.4 2560 6.5sd 2 shots only
27.6 2598 5.8sd
27.8 2595 8.9sd
28 2609 11sd
28.2 2636 12.1sd
28.4 2643 9.9sd
28.6 2682 14.9sd
28.8 2695 19.4sd
29 2698 3sd 53k psi estimate 2 shots only
29.2 2728 15sd QL estimates 2707 22"


I guess I could run the Comp ladder higher in charge, but 300-400fps is a lot to try to gain. So I guess what I'm wondering is has anybody here used comp to push teh 103 ELDX to reasonable speeds? 2300 from a 22" is just plain sad.

Since I am in 223 I've been looking at running a quick test of AR Comp vs RL15 and possibly TAC at same load just to see how they match QL predictions. 25.6 Comp is pretty crunchy and TAC appears to be less energy, but we'll see if they match QL. My main purpose is to identify if I have a bad lot or just a bad bottle of Comp or???

[StoneHendge]

It could just be that the industry has gone to crap. I just popped open a shiny new 8 lb jug of Shooters World Precision to find that it pushes a 77 grain SMK at 2460 out of my 16" JP .223 using the same charge that pushed it at 2560 out of my last keg. Same brass, same primer lot.

I feel like I should apologize to ADI for being annoyed that my latest keg of Varget was running 50 fps slower in my ARC than my prior keg.

[grayfox]

Crummy QC could be the problem, yeah. Nothing really you can do there but substitute a different lot of powder and compare. Or a differemt powder, which OP does list

But even some of those values up there confuse me still....

First off however, I will note the QL and Grt both have some trouble effectively replicating these short, fat AR cartridges. Lots of info there on the 65 Grendel forum, which is the original case that the 6Arc comes from. Most times QL/Grt will only claim about 10% or 50 fps accuracy.
One thing I have had to do is change the Sebert factor from stock, dropping it to 0.45. Now that's just me and my own model so can't transpose it for gospel as I am not a software engineer or ballistician.

But on to other points for some clarification..
I have some RE-15 results, 103 Eldx, in my 22" uintah bolt action, of 2728 fps, and an estimated 54 ksi. And 103 Eldx with Lever in this bolt action, 2735 fps; 48 ksi for Lvr.

Your Lvr data for 29.0, estimates 53 ksi, which is above the chamber max but the actual load is below the Hdy data for AR's... Now the 29.5 Hornady max is not a guarantee. But if your barrel is over max, maybe you're too high? Or maybe the OAL is not set right, possibly too close to lands (hard to imagine for the AR's, but chamber dimensions can come into play). Some early 6 Arc barrels were reported to have short throats, there are posts on here about all that.

But back to AR Comp. Taking my RE-15 data (which is in the Hdy data) as a start and substituting Ar Comp for it, I get a massive pressure increase, around 15 Ksi. Implication being the pressure is rising much faster than the bullet can accelerate to give that gas any room. Or alternatively, finding a gas gun charge below 52 ksi, I wind up with 26.something, and only 2640 or so fps. trying your 25.6 shows me only 2550 give or take (admittedly still differs from your actual in the low 2300's). All these numbers are more qualitative than quantitative... But none of this would lead me to use AR Comp in the Arc.
Last observation. And assuming that you are trying to follow the saami limits even out of your QL data... for Ar Comp you exceed 52 ksi at 24.8. It may be true that one can go over the saami limits, but you will pay a price for it later, or maybe even sooner when some load potentially blows up your gun.

So you maybe can see why I would not want to go down the Ar comp trail for your 6Arc, 103. It's safer and you'd have a "more harmonious outcome" (Quigley) using Ar comp elsewhere and buying a pound of something for your 22" 6 Arc, like lever, varget, PPV, 2520, CFE or other one promising better results for you. Unlike a couple years ago, there are powder choices on the shelf now. I can offer no conclusions on whether QC has given you a questionable keg of Comp... Maybe its results from another, known cartridge, can give you info on that. I like mine in 308 with the 110 Ttsx, and a couple other places/calibers.

Stay safe in all of this reloading.

[Diesel Pro]

LVR has become my go to powder for the 6arc. It's just outstanding for me. This is the load range that I am going to focus on for the 6 arc 103

LVR ladder CK

27.4 2560 6.5sd 2 shots only
27.6 2598 5.8sd
27.8 2595 8.9sd
28 2609 11sd

I'm "off" of the AR comp for the 6 arc, but when I use it for the caliber it was intended 223/556 it seems to suck there too.

I was hoping someone here had some solid comparative data so I could maybe tell if I had a $60 bottle of fertilizer or not...

[grayfox]

Fertilizer? Only if you want to...
It works well for 120 class bullets in 6.5 grendel (although admittedly not a published powder but several grendel horde guys use it including me).
And the lighter bullets of 308, at least for me.
I tend to go light on 308 'cause of less recoil, I'm getting up there in age.
Plus my distance pipes are creedmoors. fwiw.
I've seen plenty of talk - favorable - on ArC for calibers...
Haven't used it in 556/223 that I can recall, so you got me there.

[CZ527 Guy]

Perhaps there is a good reason why little data is being found for ARcomp loads for the 6mm ARC.

[Diesel Pro]

Sorry for the 223 data again, but here is a comparison from today. I chose 4 powders that I have on hand that all fall in the same general burn rate with RL 15 being a few steps slower:

25.6gr comparison 3rds per load 55 SBK 2.250" COAL

XBR 3006 19.1sd QL estimates 2957
RE-15 2785 28.7sd QL estimates 2796
TAC 2947 3.1sd QL estimates 2709
Comp 2755 35.2sd QL estimates 3101

Same charge 60gr Nosler
8208 2957 sd 15.7 QL est 2932

Either QL has an issue estimating Comp or I have a bottle that is "off"

Tac is the big overachieving surprise here.

[Diesel Pro]

I promise I will return to 6ARC loads using AR Comp once I get this figured out. AR Comp was recommended for the 6ARC 103 ELDX by a forum friend. I'm working in 223/556 due to available data from Alliant.

In the meantime breaking down my powder comparison using 2 different Alliant powders in 223 with 55SBK and 25.6gr charge with outside temps around 50f

Comp is negligibly slower with the same charge. Probably within the margin of error pretty much a draw. Close enough that I suspect I may have gotten a pound of RL 15 in a Comp bottle.

RE-15 2785 28.7sd QL estimates 2796
Comp 2755 35.2sd QL estimates 3101


From Alliant I found comparative load data showing both powders using a Sierra 69gr HPBT

Same speed with 2.3gr less charge required for Comp

RE 15 2956 with a 25.5gr charge
Comp 2969 with a 23.2 gr charge

Load data: https://www.alliantpowder.com/reloaders/...ulletid=91

[300BLK]

I promise I will return to 6ARC loads using AR Comp once I get this figured out. AR Comp was recommended for the 6ARC 103 ELDX by a forum friend. I'm working in 223/556 due to available data from Alliant.

In the meantime breaking down my powder comparison using 2 different Alliant powders in 223 with 55SBK and 25.6gr charge with outside temps around 50f

Comp is negligibly slower with the same charge. Probably within the margin of error pretty much a draw. Close enough that I suspect I may have gotten a pound of RL 15 in a Comp bottle.

RE-15 2785 28.7sd QL estimates 2796
Comp 2755 35.2sd QL estimates 3101


From Alliant I found comparative load data showing both powders using a Sierra 69gr HPBT

Same speed with 2.3gr less charge required for Comp

RE 15 2956 with a 25.5gr charge
Comp 2969 with a 23.2 gr charge

Load data: https://www.alliantpowder.com/reloaders/...ulletid=91

[popgun]

AR-Comp didn't work for me. I got pressure signs before getting close to decent velocities. 22" gas gun

[Diesel Pro]

After calling CCI/Speer/Alliant and more or less being told my comparisons were invalid, I sent an email with my findings laid out. These findings were shared with the "engineer" who requested samples of the powder and complimented my methodology.

Should know more on the testing soon and I will have fresh Comp to replace the stuff in question. I doubt I will pursue the use in 6ARC, but at a minimum I will definitely load some for a lot to lot comparison.

[Diesel Pro]

I did get word back that my bottle of comp is actually Reloader 15.

Some quotes: "Yes, there we where able to data back with your powder and find discrepancies with bottling. (human error) This was just a one off saturation and thanks to you was able to be caught before further incidents. Process have been improved and SOP followed."

"The powder you have is RL 15, In the Bottle. Actions have been taken to prevent this from happening again. "

I'm not sure how it was a one off saturation. I would sure think that an entire lot or at least an entire day or shift production would be called into question. I mean it's not like the guy running the line said oh yeah I remember doing one bottle wrong on such and such day...

[grayfox]

Well that is interesting for sure.
First time I've heard of a powder production line screw-up. RE15 is a bit slower, the 2 are related b/c they were trying to make a temp insensitive RE15... called it AR comp, but also they added that it is a bit faster than its poppa RE15.

Roger on the "it was only 1 bottle" thing... more like a 1 day or shift run however big that run was.

[SpeyRod]

Very interesting. Wonder how much of that got out to the market. Lots of people wondering why their loads changed…

[StoneHendge]

Nothing surprises me from the industry anymore.

I'd hate to be the guy who got AR Comp thinking that it was RL 15. Always wear your eye protection.

Did they at least send you a pound of actual AR Comp?

[Diesel Pro]

My bottle lot#