Lets discuss Barrel Time

[brantfredrickson]

Maybe I'm little dense, but I have a hard time understanding your numbers without seeing the targets.

Joe

Whether you are doing OCW, Audette Ladders, or 10 Round Load Development, what you are looking for is a minimum variation of velocity with respect to a variation in charge weight. That's why shooters use the equal intervals of charge weight in a load work up. It makes it simpler. In OCW this corresponds to a couple to a few groups next to each other that are smaller that the rest. In an Audette Ladder a couple to a few shots that are closer to each other. And in 10 Round load Development a couple or few velocities that are closer to each other. This is all with respect to an equal change in charge weight. It is the minimization of change in velocity to change in charge weight that you are looking for.

And yes the targets do most times agree with the velocity numbers. However I pull shots, move the gun when I put the trigger, and have the gun recoil into me differently due to not holding it exactly the same every time.

 

[brantfredrickson]

Perhaps, but I think his writings in this area were about unloading of the bbl/recvr joint when fired. I may be wrong. Just going from memory here. Just about every bbl I've ever seen got tighter, which would seem to concur with the joint unloading, to a point, when fired. Logically, a rh twist barrel will tighten itself to the point where this unloading stops.

That is a unique thought that you have there. I've read Vaughn on the loosening of the barrel/action joint under load of firing a cartridge, and the tightening of the barrel/action as the load disappears. The uniqueness of your thought is that temperature has an effect on this.

Truth be told, I shoot the temperature with an IR gun of the barrel/action joint because its the hottest place that easy to reach when you are shooting from a bench. Vaughn's thinking wasn't a consideration.

When you shoot 50 shots during a load development session, my thinking is that the temperature/fouling condition of the barrel changes and I see a change in the sweet spot.

And why 50 shots and not 10 shots? Its not a technical thing. I spend two hours in travel time going to and from the range. I just can't see making that investment for 10 shots.