OCW method - second rifle test

[DaavG]

Th

Round robin, 1 shot per charge, 4 shots per string, 5 minutes to cool down, repeat.

This is not using QL or GRT, just the load data in the book for the max load, and charge weight jumps that covers about 2% of the charge weight.

The target is what they sell at the Guns@Work range.

I do use GRT to compare case fill and burn rate of various powders, but I do not rely on the software to find a load, just what's on the target.

Thank you for the info. Why are you not using GRT to find a load?

[Tripodmvr]

My offer of 6 June is still open

I think you know that I have been into Quick Load for a long while. It would be interesting to evaluate your results using QL to see if there is a correlation between the two methods. Did you record speed whilst shooting? If so, I can do calculations to try and assist with load development.

[big5ifty]

Thank you for the info. Why are you not using GRT to find a load?

I would not do that, because I am a programmer by trade, and I know that no code ever written can predict the real world, it can only approximate.

GRT is not always correct.

For example, the load I worked up with N570 in my 375 RUM comes up over 100 fps short in GRT.

I know I can go and tweak the burn rate to improve the software model, but I prefer not to go test loads to collect data just to do that, as it is not necessary.

The way I end up choosing a load is simple, and gives results within 30 rounds.

[Tripodmvr]

I would not do that, because I am a programmer by trade, and I know that no code ever written can predict the real world, it can only approximate.

GRT is not always correct.

For example, the load I worked up with N570 in my 375 RUM comes up over 100 fps short in GRT.

I know I can go and tweak the burn rate to improve the software model, but I prefer not to go test loads to collect data just to do that, as it is not necessary.

The way I end up choosing a load is simple, and gives results within 30 rounds.
[/quote]

I have done close to 1500 calculations with QL, of which about 95% gave accuracy at the predicted speed. The best I have achieved so far was to calculate and get confirmation for a load with a 375HH. It only took 8 shots to get the hunting load and that included a grouping of 3 shots. With the cost of your calibre's components, that will be a big saving. Nodes are normally a band and QL gets you close. Actual shooting with increments of say 0,3gr will establish the band width and show the best accurate load.

[Tripodmvr]

I should have qualified my statements above.

1. Predictions for loads using defaults on QL are not accurate and might be useful to check supplied factory loads.
2. My calculations are done using the following data :
   a) Measured barrel length
   b) Measured water case capacity of a fired case
   c) COL of cartridge from base to tip of bullet (used to calculate case fill)
   d) Charge used and speed achieved

Those figures are then entered into QL and a charge calculated to get the barrel time correct for the specific length of barrel. This is calculated using the OBT calculations derived by Chris Long. http://the-long-family.com/optimal%20barrel%20time.htm

[big5ifty]

I've read the content at that link.

OBT is the mathematical explanation of OCW, as per the author.

The reason I would not use OBT instead of OCW remains.

A calculator is a model. The model requires measured inputs, subject to error. The model can only approximate the real world, some better than others.

[Tripodmvr]

Below the actual data as shot and QL predicting 0,2gr more to get to the node at 1.022ms. Practical accuracy and in the node band of normally 1gr in width. That is why I wanted to reverse engineer some of your data where you achieved accuracy. All the data used was from actual measurements and not a prediction.

TPL56mm   Kriek 48gr      25gr Riflex RFL      3234vps gemeet   Skote sny amper      25,2gr   3266vps

[Treeman]

you guys are beyond my abilities.