Would Quick Load provide a target velocity window for my load/barrel?

[Linko]

I want to know the optium velocity window for my rifle/load

30" 7 twist 223 bolt action 1.922 cbto
80 gr SMK / H4985 / GM205M Lapua

would quick load provide a optimum velocity range?

 

[CharlieNC]

Google Chris Long Optimum Barrel Time. Method has worked well for myself and many others. Some will say it is vodoo.

 

[Ned Ludd]

Only if you have a target velocity in mind. QuickLoad was not designed to directly identify optimal velocity windows or accuracy nodes for a given setup. Rather, it was designed to provide predictive outputs in response to changes in input variables for things like velocity, charge, weight, case volume, etc. In order to use QuickLoad for identifying an optimal velocity window, you have to have some measure or readout that links the desired output to the inputs.

In your particular case, the outpit to use is barrel time (in milliseconds). The reason for this is that you can use an Optimized Barrel Time chart for your specific barrel length to identify the target (desired) barrel time you want, then input you load testing data into QuickLoad and use its output barrel times to adjust the load until you achieve the desired barrel time, or just ever so slightly slower. The caveat to all this is that there are many, some of whom I'm sure will add their $.02 here, that don't believe that OBT Theory is valid or works for load development because they don't like how it has been "explained" to work. If you're interested, check here: http://www.the-long-family.com/OBT_paper.htm. I rather suspect it is more likely that the true explanation is a function of barrel harmonics, rather than an expansion donut traveling back and forth in the barrel steel. However, I don't particularly care how it works, I have used it for years and in my hands it does work very well indeed. QuickLoad allows you to use the OBT table because it gives you barrel occupancy time as one of its outputs.

I ran some of your numbers in QL, making a few educated guesses as well on inputs. I came up with about 23.6 gr H4895 and 2909 fps velocity. So with your setup, you're probably looking in the neighborhood of 2900 to 2920 fps with H4895, predicted optimal being about in the middle. However, I fudged numbers for you actual COAL and case volume so you need to run the numbers with your actual data before loading up any rounds. You could certainly get more velocity before hitting MAX pressure, but I strongly doubt you could reach the next faster OBT node before going way overpressure.

 

[Linko]

Only if you have a target velocity in mind. QuickLoad was not designed to directly identify optimal velocity windows or accuracy nodes for a given setup. Rather, it was designed to provide predictive outputs in response to changes in input variables for things like velocity, charge, weight, case volume, etc. In order to use QuickLoad for identifying an optimal velocity window, you have to have some measure or readout that links the desired output to the inputs.

In your particular case, the outpit to use is barrel time (in milliseconds). The reason for this is that you can use an Optimized Barrel Time chart for your specific barrel length to identify the target (desired) barrel time you want, then input you load testing data into QuickLoad and use its output barrel times to adjust the load until you achieve the desired barrel time, or just ever so slightly slower. The caveat to all this is that there are many, some of whom I'm sure will add their $.02 here, that don't believe that OBT Theory is valid or works for load development because they don't like how it has been "explained" to work. If you're interested, check here: http://www.the-long-family.com/OBT_paper.htm. I rather suspect it is more likely that the true explanation is a function of barrel harmonics, rather than an expansion donut traveling back and forth in the barrel steel. However, I don't particularly care how it works, I have used it for years and in my hands it does work very well indeed. QuickLoad allows you to use the OBT table because it gives you barrel occupancy time as one of its outputs.

I ran some of your numbers in QL, making a few educated guesses as well on inputs. I came up with about 23.6 gr H4895 and 2909 fps velocity. So with your setup, you're probably looking in the neighborhood of 2900 to 2920 fps with H4895, predicted optimal being about in the middle. However, I fudged numbers for you actual COAL and case volume so you need to run the numbers with your actual data before loading up any rounds. You could certainly get more velocity before hitting MAX pressure, but I strongly doubt you could reach the next faster OBT node before going way overpressure.

It took me a little time to load and shoot some rounds so I would have some cases fire formed and with a spent primer.

My measurements:

COAL = 2.56

I weighed 7 cases dry and filled with water, here are those measurements:

Dry - - Filed - - Difference
97.32 138.03 30.70
97.72 128.66 30.94
97.64 138.32 30.68
97.72 128.88 31.16
97.92 128.72 30.80
97.20 128.38 31.18
97.54 128.32 30.78