- Thread starter Lrush
- Start date
Yes.
Look for the Optimum Barrel Time for your barrel length:
http://www.the-long-family.com/OBT Table.pdf
Make sure you input accurate bullet length, OAL, and case capacity info.
http://www.the-long-family.com/OBT Table.pdf
Make sure you input accurate bullet length, OAL, and case capacity info.
Chamber an empty case, slide a dowel down the barrel until it stops, make a pencil mark at the muzzle, remove dowel from barrel, measure the part of the dowel that was in the barrel to the pencil mark with tape measure.
Some folks like to subtract the length of the base of the case (boltface) to the base of the loaded bullet where the bullet goes full diameter, not counting the boattail, to get true bullet travel distance to bullet exit.
Or so I have been told...
Some folks like to subtract the length of the base of the case (boltface) to the base of the loaded bullet where the bullet goes full diameter, not counting the boattail, to get true bullet travel distance to bullet exit.
Or so I have been told...
From the bolt face. Use a cleaning rod.
I don't subtract out the case distance. If I do that my barrel length is 2" shorter and the QL does not jive with what the load does on paper.
I personally have always measured with an empty case in the chamber, but there is only about 3/16" difference roughly so it doesn't really make much difference.
Folks do all sorts of strange and wonderful things in the never ending pursuit of accuracy...
It's all fun and interesting.
Folks do all sorts of strange and wonderful things in the never ending pursuit of accuracy...
It's all fun and interesting.
For use in OBT, DO NOT use a casing to measure barrel length. You're establishing a basis for calculating how long it takes the shock wave to travel up and down the length of your barrel (at the speed of sound through steel). The thickness of the base of your cartridge has NO IMPACT on this phenomenon.
If you don't read Chris Long's instructions, you'll have no idea why you're doing what you're doing. And when your real world data fails to match QL's predictions -- which I guarantee it will -- you won't have the background to know where to look for the fix.
Read Chris Long's instructions, and search this forum for how I and others apply OBT as a matter of practice.
If you don't read Chris Long's instructions, you'll have no idea why you're doing what you're doing. And when your real world data fails to match QL's predictions -- which I guarantee it will -- you won't have the background to know where to look for the fix.
Read Chris Long's instructions, and search this forum for how I and others apply OBT as a matter of practice.
