Range Report 18" AR, 77gr CC, 8208XBR

[BoilerUP]

Had the opportunity today to try some IMR 8208XBR in my AR, and figured others might be interested in the results.

18" 1:8 5.56 Black Hole Weaponry barrel w/ rifle length gas

Environmentals:
525' ASL
30.30" Hg
30°F temp
72% humidity
mostly cloudy

I fired three control groups to sight in my scope and establish a velocity baseline. First was 5 rounds of Hornady 75gr Steel Match. These averaged 2489fps on the chronograph today, though previous data from this rifle has consistently been 2590-2600fps with this ammunition.

I then shot another control, the "standby" 24.0gr Varget with 75gr Hornady BTHP. 10 rounds of this came in just under 1" and averaged 2579fps across the chronograph. Good considering ES was 128...

The last control was 5 rounds of Black Hills 5.56 77gr Match HP SECONDS. These grouped 0.8" @ 100yd and averaged 2688fps across the chronograph.

Then I moved onto XBR loads.

IMR 8208XBR
77gr Nosler CC @ 2.255"
Rem brass, 1x
Rem 6 1/2

First charge weight was 23.2gr 8208XBR. This is the listed max charge per Hodgdon, but multiple internet reports show this to be an OCW with plenty of room to step on it. 4 rounds across the chronograph measured 2584fps with ES of 25. Accuracy was 3 holes touching with a flier 9:30 and 0.75" out.

Next was 4 rounds at 23.5gr 8208XBR. These four rounds averaged 2658fps. Three rounds were cloverleafed, with a single flier 9 o'clock and 1" out.

Finally, 4 rounds at 23.8gr 8208XBR. These four rounds averaged 2683fps with ES of 22, and grouped the best at 0.44" @ 100yd. Brass looked good, better than the full-house BHA 5.56 brass and only 5fps slower on average.

I'm thinking I'll load up 10 rounds each at 23.5gr and 23.8gr and see how they perform..

 

[LngRngShtr]

Re: 18" AR, 77gr CC, 8208XBR

Glad to see this I just finished a build with that same barrel and have yet to load up ammo for it

this combo is now on my list to test when I can get some component..

John

 

[Niles Coyote]

Re: 18" AR, 77gr CC, 8208XBR

I will check my notes but sounds like you are getting the same as I in a FHN 18" upper with the same bullet/powder combp but with LC brass (07 headstamp).

 

[Niles Coyote]

Re: 18" AR, 77gr CC, 8208XBR

23.7= 2670, 23.8= 2673 & 23.9= 2685

This with LC brass WSR primmer imr8208 and the 77 CC seated at 2.255ish inches. My ES was 16 for 23.7 and 23.9 and I think light may have messed up my crono on the 23.8 as the ES was 49. I dont recall which shot best right off hand but all three were good.

 

[BoilerUP]

Re: 18" AR, 77gr CC, 8208XBR

Thanks Niles...looks like my data lines up well with yours.

Did you ever test up to 24.0gr? I'm now thinking I'll test 23.8gr and 24.0gr and see which of the two provides better accuracy (and if either proves too hard on brass).

 

[Niles Coyote]

Re: 18" AR, 77gr CC, 8208XBR

I am sure I did but since it’s not in my notes it must have not been of any interest to me group wise. I was trying to find something around the 2750 range but that so far has been out of reach... that is without pressure signs.

I generally shoot an OCW then refine and crono on that second test. FWIW, I would still try 23.5 as I just found another entry for 23.4 and 23.6, this was on a different day and my crono may have been set closer to the rifle as the velocity is [email protected] and [email protected] with a ES of 12 for that last one.

Looks like I need to also start including group size in my notes... unless I can find my targets at home I am not sure right now which of these shot the best.

 

[Niles Coyote]

Re: 18" AR, 77gr CC, 8208XBR

I tried ar comp but found pressure at a lower velocity than 8208 was giving me.

 

[BIPMaster]

Re: 18" AR, 77gr CC, 8208XBR

I just got some CC's on a whim since they were in stock at the local Cabelas. I also have a good amount of 8208 since it is usually available here local. Glad to see the combo has good accuracy potential.

 

[M_16_4_REAL]

Re: 18" AR, 77gr CC, 8208XBR

Try tac. Its what they use in the mk262 load and it give really good velocity out of 18-20" barrels in my experience.

 

[vvillium3]

Re: 18" AR, 77gr CC, 8208XBR

Great info guys. Need to try and get my velocities up down range as I haven't been getting what I thought I would out of my 18" ar shooting 77gr sierras and varget. Once I get through this coyote season, I'll have to experiment with this for next year.

How temp sensitive is TAC & 8208 compared to varget?

 

[Cegorach]

Re: 18" AR, 77gr CC, 8208XBR

Thanks for sharing your data, I know 8208 has worked very well for me is 223 and 223 ai.

 

[2ndPanzer]

Re: 18" AR, 77gr CC, 8208XBR

24.0 was a great node for me with 8208, didn't get hot until 24.3, and 24.5 was loosing primers. It has a very small window of showing signs to way too much. It shot the same from 23.9-24.1, so I settled on 24.0 and have had great results. Still not as good as H4895 @23.5 but lots easier to make a bunch of with 8208.

 

[BoilerUP]

After 100 & 200yd testing, I think I've settled on 23.5gr 8208XBR with a 77gr Nosler CC. Haven't nailed down velocity yet, but it looks to be 2670, +/- 10fps and accuracy has proven to be at least MOA (I'm still developing gas gun skills).

23.8gr has proven to equal Black Hills 5.56 77gr Match HP Seconds velocity, but accuracy isn't quite as good as the 23.4-23.6gr range. I have also tested up to 24.0gr without obvious pressure; accuracy has proven better there than at 23.8gr, but the lower node keeps me supersonic to 700 which is the limit of my scope elevation anyway.

Also - this barrel appears to hate Hornady 55gr FMJs with XBR...I've shot 24.2gr to 25.8gr in 0.2gr increments, and the average group size is over 2" @ 100yd...bout the same as UMC 55gr Metal Case. 25.6gr appears to be the "most" consistent with 55s, but further testing will have to confirm that.

 

[BobinNC]

IMR 8208XBR
77gr Nosler CC @ 2.255"
Rem brass, 1x
Rem 6 1/2

Be real careful with your loads if your still using Rem 6 1/2 primers. Of couse you may have mistyped and are using Rem 7 1/2 primers

If you are using 6 1/2's: Look at your boxes of the 6 ½ primers. Do you see a warning in fine print like the one below?

“Do not use 6 1/2 small rifle primers in high intensity rifle cartridges such as .17 rem, .222 rem and .223 rem, as damage can occur to firearm or persons”

The 6 ½ REM primers are designed to be used in lower pressure, lower powder capacity rifle cartridges like the .22 Hornet, the 218 Bee and the 25-20 WIN

 

[BoilerUP]

I've burned through all the Rem 6.5s without any issues.

I'm onto CCI-400s for my AR loads, though I plan to standardize all my small rifle primer needs to CCI-450 once they become available again.

 

[BobinNC]

I've burned through all the Rem 6.5s without any issues.

I'm onto CCI-400s for my AR loads, though I plan to standardize all my small rifle primer needs to CCI-450 once they become available again.

I hope they are available again soon. I'm down to my last 1,000 CCI-450's for my .223's

 

[vvillium3]

Had a chance to try some of this powder out. Here's the stats:

AR
18" WOA match
Winchester brass
WSR primer
77gr SMK'S
Loaded @2.26"
23.8gr 8208xbr (seems to be the sweet spot for my rifle)
2720 fps (pretty sure my chrono reads fast. My .308 loads are about 40 fps faster than normal reports)

Now here's the dilemma. Anyone try this powder with Berger 70gr VLD's? I'm getting my best loads with these bullets over 25.6gr varget (2760 fps). If I can get over 2800 fps with the VLD's and 8208 I'll be in business. Is it worth a try?

Thanks,
Jason

 

[2ndPanzer]

Worth a try for sure. 25.0 is a good spot to start.

 

[Niznac]

 

[trdjohn]

wow that is a necro thread if I've ever seen one

 

[Steel head]