Temp Sensitivity in 8208 XBR & Cartridges in similar capacity, 6x47 Lapua & 6 CM

[Romulus]

Temp Sensitivity in 8208 XBR & Cartridges in similar capacity, 6x47 Lapua & 6 CM

I have been searching for any articles, user tests, or other data regarding 8208 XBR temperature variations. I know the marketing copy from reading and waiting for it to come out. I shot it with great results in a 308 up to 168 gr pills where I noticed quickly that other powders were better suited for heavier bullets. It shot the 135s I bought just for fun quite amazingly and spit the 155s (2156 and Hybs) faster and more reliable than expected.

The case capacity range I'm looking at for a new project is between 6x47 Lapua and 6 Creedmoor with 105s. If you have experience with XBR in this range I'd appreciate the info, but could you please label the post "6 Cartridge Name: pertinent info" for easy reference later? Thanks.

Anyhow, curbing the rambling, I'd appreciate any links, images, or anecdotal experiences regarding 8208 XBR. I'll post a few of the common articles below.

--- 8208 XBR copy, it reads like an old shooting magazine: http://www.imrpowder.com/8208xbr.html

--- Feel good graphs of temp sensitivities in 30-06, 300 Win, 308 Win, 22-250: http://www.hodgdon.com/smokeless/extreme/page2.php#top

--- Perennial Temp Sensitivity lineup on forums (I don't know provenance, case capacity, etc):

Velocity spread in FPS between 0-125 degrees F:

1. H4350: 4 (FPS)
2. Varget: 8
3. H4831C: 10
4. RL 12: 26
5. AA4350: 29
6. AA2460: 36
7. IMR 4064: 46
8. VIT 550: 49
9. RL 15: 50
10. VIT N140: 50
11. AA2520: 63
12. IMR 4350: 67
13. RL22: 75
14. RL 19: 94
15. AA3100: 113
16. W 748: 114
17. VIT N560: 121
18. IMR 4831: 127
19. IMR 4895: 166​

But at the end of the day I have nothing directly related to XBR. Thanks for any help.

 

[357Mag]

Romulus -

Please ckk your PM"s.


With regards,
357Mag

 

[spclark]

I bought some 8208XBR early in 2008 when it first appeared, thinking it'd maybe be good for Palma. Took me almost two years to prove that was good thinking! Meanwhile I'd been messing with 6XC & loaded up fifteen cartridges just before leaving for a day of load testing with four other propellants in a then-new 30" 1:7.8 Bartlein.

No load data to base a starting load on either, just SWAG & numbers shown for anything close in case capacity.

Turns out the 8208XBR was the best of the five propellants I'd brought, the lowest charge (37.0 grains, hBN-coated Berger 105VLD's seated 0.020" off) clearly the least vertical @ 600 yards.

That day was ~ 75F & windy as all heck. I shot that load for almost a year until losing two primers (large rifle, Norma brass) one Saturday at Lodi shooting to 1,200 yards. That day was ~ 90F so I've backed down to 36.7 grains & found nothing to complain about since.

Tried two of the 38.0 rounds that test day but heavy bolt lift made me quit. The 39.0 rounds were taken home & 'recycled'.