8208XBR vs N-133, Plus More
Here is some information that I think you guys might find interesting.
I have shot N-133 for years at an average of 29.2 grs. Since N-133 can be "difficult," I was anxious to try some of the new 8208XBR, and purchased lots 4736 and 4798. N-133 at 29.2 grs comes halfway up the neck in my 6 PPC. It took 31.2 grs. of both lots of XBR to come to the same level, which means load density of both lots was identical.
Next, I chronographed each, and the velocities were as follows:
N-133 @ 29.2 grs. = average 3340 fps
Lot 4736 @ 31.2 grs. = average 3371 fps
Lot 4798 @ 31.2 grs. = average 3393 fps
The temperature was a steady 55 degrees with 50% humidity.
Even with "untuned" loads of 8208XBR, I got less vertical and better groups than with N-133 right off the bat. Of the XBR loads, lot 4798 produced tighter groups than 4736. Even the primers looked better with the extra XBR than with N-133.
My second trip to the range was to chronograph 5-shot groups of Lot 4798 only, because it shot the best above. Temps this day were 55-65 degrees with humidity 48-43%. Results were:
Grp. # 1 of 30.0 grs. = average velocity 3170 fps
Grp. # 2 of 30.3 grs. = 3207
Grp. # 3 of 30.6 grs. = 3268
Grp. # 4 of 30.9 grs. = 3279
Grp. # 5 of 31.2 grs. = 3325
Can't explain why 31.2 grs. produced 3325 on a bit warmer day than 31.2 grs. at 3393 fps on a little cooler day. Anyway, the groups were ok and I think the best load is somewhere between 30.9 and 31.2 grs. Next trip to the range will be to nail down a tune...for that day, anyway.
Just thought I'd throw this in for discussions sake.
MBrenner