1858rem said:
whats optimal barrel time, how accurate is it?
Take a look at this website ...
http://www.clik.to/optimalchargeweight
and this website ...
http://www.the-long-family.com/
Here's an excerpt from Dan's page ...
"Engineer Chris Long's model of barrel
behavior suggests (simply put, and in part)
that the initial shock wave, generated by the powder
charge's ignition, travels at the speed of sound in
steel (about 18.000 fps) from the chamber to the muzzle,
then back, in a repeated pattern. When this wave is present at the muzzle,
there is naturally much turbulence and obturation of the
"roundness" of the bore at the muzzle. However, when
this main shock wave has reverberated back to the
chamber end, the muzzle is relatively stable.
This
window of opportunity, according to Chris, is the best
time for the bullet to exit the muzzle. The barrel is
basically straight, and relatively calm.
(Read later about the "scatter node" which is the point
at which the bullets are being released from the bore
when the shock wave is at the muzzle. I call this area
the "scatter node" because it will produce a scattered group,
throwing flyers at random. This is the most
inopportune point of all for bullet release, the scatter node area
can be easily seen during an OCW test, and generally 1 to 2
powder graduations above the scatter node charge will have
you right in the OCW zone. The existence of the scatter node
is the main reason the conventional ladder (Audette) test often fails
to yield useful results)."
There are believers and non-believers ... so it's really down to the individual to find the system that works best for them.