6mm BR and IMR 8208 XBR

[Lone Hunter]

Does anyone have any load data for IMR 8208 XBR for 6mm BR with Berger 105 Match Hybrid bullets? I've searched and cannot find data for this powder. It works great out of my Grendels. Any help would be appreciated . Also, if you have data for IMR 4166 that would be great. Currently running Varget out of the 6BR. 28" barrel,Lapua Brass, Berger 105 hybrids. Any help would be greatly appreciated.

 

[X-Caveman]

I run 28.5gr XBR8208 under a BIB104 sparked by a Tula magnum in my 6BR. 28" Rock Creek 5R. This combo has earned me some small group & high score target hardware in our 500M Fly Shoot. Only about 2,825 FPS, but it seems to shoot well. I ran it up to about 29.7gr but found pressure and no better accuracy. Clean burning and meters great. I really like it.

 

[Kurz]

Personally, I really like using the IMR8208XBR powder but mostly with light bullets in the .308 Win. for Match shooting. I ran a few tests a while back with the 6mmBR because I thought it would be superb. Well, it doesn't fill the case before reaching the very top of the pressure curve but in the same range as stated above about 28.5 + is good accuracy. I'd like to see a bit more velocity but the you will need to switch powders for that. Try it, you'll like it!

By the way, my seating depth is adjusted according to my custom reamer, it is not SAAMI.

 

[spclark]

I’d start at 27 grains then work up.

I used 8208XBR for 6XC & Berger’s 105VLD Target then 308WIN for Palma shooting (2156’s, Berger’s 155.5) for years with excellent results.

Obviously those two needed more than 27.0 grains given their respective case capacities.

Every rifle’s different, what works for one combo may not for someone else’s. Working up from a safe load (27.0 surely ought to be!) is always better than jumping to a conclusion that might ruin your day.

 

[farmerjohn]

I’d start at 27 grains then work up.

I used 8208XBR for 6XC & Berger’s 105VLD Target then 308WIN for Palma shooting (2156’s, Berger’s 155.5) for years with excellent results.

Obviously those two needed more than 27.0 grains given their respective case capacities.

Every rifle’s different, what works for one combo may not for someone else’s. Working up from a safe load (27.0 surely ought to be!) is always better than jumping to a conclusion that might ruin your day.

What he says, I fire form with 30.0 and Bart's 103s for my bra, new Lapua. 29.5 in my br, 8 twist, 105 Berger vld hunting....
John

 

[SealT5]

My accuracy fireforming loads for my Dashers is 28gr 8208XBR & cci450. Great powder

Joe S

 

[JFrank]

I run 28.5gr XBR8208 under a BIB104 sparked by a Tula magnum in my 6BR. 28" Rock Creek 5R. This combo has earned me some small group & high score target hardware in our 500M Fly Shoot. Only about 2,825 FPS, but it seems to shoot well. I ran it up to about 29.7gr but found pressure and no better accuracy. Clean burning and meters great. I really like it.

I hope you don't mind if I try out that recipe.

 

[X-Caveman]

I hope you don't mind if I try out that recipe.

I checked my notes again. I started seeing pressure at 29.3 with the bullet at .02" into the lands. That gave me 2,895 FPS. 28.5 should be safe, but be careful!!!

 

[farmerjohn]

I checked my notes again. I started seeing pressure at 29.3 with the bullet at .02" into the lands. That gave me 2,985 FPS. 28.5 should be safe, but be careful!!!

You made me go back and check my notes, the one thing I noticed was that 8208 seems to be sensitive to seating depth. I did some testing with a straight br and found the same thing as you, but at 29.5 I am jumping the bullet .015. As I moved in my pressure started spiking pretty quick. As it was a culling rifle and shooting around half in I left it there.

 

[Lone Hunter]

You made me go back and check my notes, the one thing I noticed was that 8208 seems to be sensitive to seating depth. I did some testing with a straight br and found the same thing as you, but at 29.5 I am jumping the bullet .015. As I moved in my pressure started spiking pretty quick. As it was a culling rifle and shooting around half in I left it there.

That's what I noticed with 8208 in the Grendel. It pressure spikes pretty fast.

 

[X-Caveman]

You made me go back and check my notes, the one thing I noticed was that 8208 seems to be sensitive to seating depth. I did some testing with a straight br and found the same thing as you, but at 29.5 I am jumping the bullet .015. As I moved in my pressure started spiking pretty quick. As it was a culling rifle and shooting around half in I left it there.

Corrected velocity. Dyslexia got me again. This load likes it between .016” & .018” in the lands in my bbl

 

[urbanrifleman]

I really suggest you try AR Comp at the same time.

I know people have the love affair with h4895 and 8208 but after testing AR Comp i have no idea why it's not in that same group. It is tested to to be 5 times less temperature sensitive than either one of those powders, has a decoppering agent that literally allows NO COPPER in the barrel (people think its "dirty" but its the decoppering agent) it burns so clean you can't tell the case was fired and the velocity spreads are the smallest I have ever seen.

The burn rate appears to be right at 8208 to h4895 right in between.

Try it.

 

[Lone Hunter]

Urbanrifleman, Do you have any load data to go with Berger 105 Hybrids or a link to this powder? My Berger manual does not list it. I looked at Alliant's site and they have no data for 6mm BR. Thanks

 

[spclark]

Alliant’s recipe for 308WIN, Sierra 155 (2156 I assume) and AR Comp is 43.2 grains, 2,920 fps.

Hodgdon’s MAX recipe for 308WIN, the same Sierra 155 bullet and Varget is 47.0 grains, 2,909 fps. (I’ve used 47.5 before abandoning Varget for Palma loads years ago; I know folks who use even more IF they can keep a bullet in the case! This is COMPRESSED in most brands of 308 brass.)

So roughly 4 grains less AR Comp in a case with a capacity of 47 grains Varget for roughly equal velocities using same bullet.

Gold Standard recipe for 105-107 grain bullets in 6BR with Varget is 30.0 grains, or ~ 2/3 that of a suggested load for a case having a tad more than 50% greater case capacity.

Knock 1/3 off that 308WIN AR Comp load of 43.2 grains, you get 28.5 grains:

43.2 x .66 = 28.5

(6BR’s a pretty easy cartridge to load for.)

I’d start with 28.0 grains AR Comp and your Berger 105’s jumped 0.030” then work up from there.

Ought to be safe enough.

 

[Lone Hunter]

Thank You spclark. I use Varget in my 6 BR loads jumped .030. H4895 just didn't shoot as good. Appreciate the info and will try it.

 

[spclark]

Appreciate the info and will try it.

Let us know what you learn once you have, OK? Adds data we can benefit from.

 

[holstil]

Tag