Ran some 400g Hawks thru my 505 to find wussy load and thought why not try out the optimum barrel time equation. I thought if the equation can estimate accurate load, should also be able to estimate an inaccurate load. I loaded up 2 sets of optimum loads and 1 half way between.

the first target was optimum harmonic 7. Imagine my surprise when i saw this group (first shot of the day).

2nd target was inbetween harmonics for worst load. group measured 2" cc.

3rd target was next optimum harmonic. This was around shot 17 and i think my shooting was getting a bit twitchy, but looks like a reasonable group. group measured 1" cc.

I used Quickload to calculate the barrel time (adjusted the parameters from previous shooting data. originally used 460 wby data but this did not match the gibbs and still do not have pressure,velocity but somewhat close).

Even with the velocity off a bit, this one time data point seems to indicate some usefullness of this equation.

rgds

steve

PS. my picture posting still needs refining, so only first target.

quote:

optimum barrel time equation

What's that?

sorry, here is a link. An engineer, Chris Long, developed a shock wave theory of barrel resonance, made a MatLab model, and then verified with experiment.

He published a simple harmonic equation that uses barrel length and the time for the bullet to exit the barrel to determine the velocity at exit that gives the minimum bullet dispersion.

To early to tell if saves time on load development, but my first time out, shows some promise.



link to shock wave theory