Reduced load calculations

[BruceP]

Has anyone done reduced load calculations using the formula given in the Lee modern Reloading manual and test fired them over a cronograph?
I put this formula onto an Excel spreadsheet and then took two different manuals and tested it using listed loads and using the starting load vel. as my target vel. I was surprised at how close most of the test figures came to the listed powder charge of the starting load. It seemed to work pretty well with cartridges of all different expantion ratios.
BruceP

[ricciardelli]

It's one thing to get results on a computer...it is a totally different story at the range with a chrony...

[PaulS]

BruceP,
Some powder / cartridge combinations are extremely linear and predictable and some are not. It is never advisable to extrapolate data without testing in gradual steps, following manufacturers recommendations, and watching for danger signs.

PaulS

[BruceP]

Steve & Paul your points are well taken.

Steve your point is exactly why I was asking if any one had tried this and chronoed the loads.

Paul You are also right and I would never suggest that anyone try this without reading the manual and the cautions that go with it, ie. not using slow burning powder for reduced loads and not to try and use the formula go go up in loading, to name two.

I was just amazed that when using powders of mid-burn rate for the caliber
the calculations came so close to velocitied listed in the manuals, and wanted to know if it and been proven by actual shooting results by anyone here.
BruceP

[Flash]

Yes Bruce, I've tried it with a 7.62x39 SKS. I had to cycle the action by hand the recoil was so light. I wanted to shoot a cast load at a low velocity but later found out that I might be choking off the gas ports with lead. I shelved the idea due to that but the formula worked fine. I wouldn't use a large capacity case but small bottle neck cases work fine. My loads were just over 750 fps with a 160 grain gas check bullet.