This is really an area of uncertainty. It's worth getting on the buzz and searching some posts by Moray. He's done a lot of testing on differences between locked brummels vs. straight buries and whatnot.
The basic concept to understand is as follows:
Straight bury stronger, but less secure.
Locked brummel almost as strong, but WAY more secure.
Unless I'm trying to eek out the last bit of strength out of a sling, I'll choose the locked brummel over the straight bury every time. With a straight bury, you should easily be able to obtain 100% of the ropes strength. With a locked brummel, 90% should be easy to get.
As to how much to bury after? If you do the lock, you don't need the full three fids. You could easily cut it in half with no worries. Some would say 1 fid would be fine, and I've had good results in testing going all the way to 1/3" of a fid after the lock.
Most of the manufacturer's don't "encourage" the locked brummel for one reason or another, but most tree guys would much rather have it. We tend to prize security over strength.
Do the lock, you could even do a double lock, then do about 1 fid tail with a beautiful taper, of course.
love
nick
