I'm replying off-list 'cause I haven't kept up w/ the thread (I'm behind in my e-mail).  But I used to do professional packing and shipping; plz see below.

> > Your best bet would be 11" x 11" x 11" boxes (or 12" x 12" x 12"), the
> > records packed vertically (standing on end) tightly within but without
> > bulging and then use crushed newspaper to pad, as you suggest.
> >
> Is there any particular reason that 11" x 11" x 11" would be better than
> 10"x10"x10"?  The 10" inch box would certainly make for a tighter fit.
> Is the concern based on the fact that, with a 10" box, the edge of the
> records would be touching the interior walls on all 4 sides?  The 10"
> boxes are about 20 percent less expensive than the 11" boxes - but since
> my main concern is that the records arrive in good shape, that price
> difference is certainly not my deciding factor.

For really valuable/fragile stuff, we used to "double-box" them.  In the case of LPs, since you don't want static-y, crumbly stuff like styro peanuts mixed in, I'd suggest packing them in a snug box (10" x 10" x 10"?), lined w/ a plastic kitchen garbage bag (in case someone ELSE'S box leaks during transit!).  Then put styro peanuts -- or in the case of LP albums, chunks of styro inserts, such as are left over from receiving A/V eqpt., in between the inner and outer box.

Hope that makes sense!