by shaman » Thu Oct 01, 2009 5:28 pm
One reason I backed off BL-C(2) in my various .308 loadings is that I was amazed at how variable the velocities were shot to shot. I am a big proponent of buying a chronograph. I have one of those cheapie Chrony units-- it's accurate as all get out, but just doesn't have any bells and whistles. It made my reloading life much simpler. This was one of those times where the chronograph told the story.
If you have two loadings, one with something like H4895 and an similar load done up with BL-C(2) and you see a 5-20 fps variation in one load and 50-75 fps variation with the other, which one are you likely to pick? I've had this happen with both 308-based loads and .358-based loads. BL-C(2) got relegated back to loadings for the .223 rem on my bench. Of course, the next guy will swear by BL-C(2), and there is always enough difference in each others' reloading techniques that it makes sense that what works for one may not for the other.
I used to work in a wire foundry, and the boss used to tell us: "Son, if you farted off your left cheek when you made this wire on Monday, you sure better remember to let one rip off your left cheek on Wednesday." I think that was a bit of an exaggeration, but he was the boss. One thing was for sure: I had no idea how to vary which cheek, so I waited until my breaks to fart. Don't ask me which cheek I use at my reloading bench.
As I understand it 308 WIN is a bit harder to load than the 30-06 and the difference has something to do with the neck dimension-- don't hold me to this. Somebody threw that out one time when I was complaining about finding a good load for my Savage 99. I do know I was able to find a 30-06 load that shot wonderfully in all my '06 rifles right away. 308 WIN made me grow as a reloader.
I would not be at all surprised that 130 grainers are not going working. If you look through enough loading manuals, there are always fewer choices for the 308 WIN than the 30-06. 308 WIN is pretty much a 150-180 grain animal, whereas you can load '06 from 110 up to 220 grains and still have a decent load. All these short-action rounds suffer a little bit from this tendency, but folks find the working window to be adequate-- otherwise we wouldn't have seen the Wizzums and Ultra WIzzums and Super ultra WIZZZZZZZums. In a lot of ways, this sort of thing makes you appreciate the genius behind the 30-06 Springfield all the more, especially when you consider the state of art in powder, bullet, and instrument technology in 1900.
If you start digging into this deeper and deeper you eventually start hearing about barrel harmonics, and methods of loading that take this into account. One method I have investigated involves loading 5 rounds at a certain load, adding .2 grains of additional powder and loading 5 more rounds and so on (never exceeding the MAX load) . Somewhere in there, you end up with a .2-.6 grain window where it all comes together and groups as good as it is going to get and then the groups start widening. I don't have a link, but I know the method is out in the 'net if you go looking. As a deer hunter, and not much of benchrester, I can tell you that I've never needed to go that far. Usually nocking off 5% off MAX is enough to get a working deer load.