OK Mustanir, if you're sure you're going to do this let me give some suggestions that might help you not loose a hand or an eye.
You have two different issues here, the diameter of the bullets, and the amount and burning rate of the gunpowder.
First the bullets. I just pulled a round of commercial Fiocchi 7.6X39 and measured it's diameter at .309". Well, that actually sounds doable in terms of recycling your bullets if the diameter is not much bigger than .308".
The powder is harder. What I found was 24.0 grains of ball powder pushing that 124 grain bullet. Flipping through several reloading manuals the maximum charge I'm finding for a 123-124 grain bullet at 24 grains is IMR 4198. This does NOT mean the powder in the case is 4198, but it MIGHT have a burning rate approximately the same as IMR4198. So, IMR4198 data might be a starting point for loading it into the .30-06.
Now, the bad news. I didn't find any loading data for jacketed bullets for IMR4198, mostly because that powder is way to fast for the best performance. There are however a few cast bullet loads using 4198 and you might use that data as a starting point. For Lyman's 151 grain lead bullet their starting load of 4198 is 23.0 grains for 1670 fps. This only produces 12,100 CUP of pressure. Their max load is 37.0 grains giving 2515 fps and 38,000CUP. I'd suggest that using my pulled 124 grain bullets with between 24 and 37 grains of my recycled powder would make something that would go bang without going boom.
Don't use my numbers automatically. You need to pull your bullets, measure their actual diameter and measure the amount of gunpowder in your ammunition. Then you can come up with a rational stratage for making a load that won't blow up in your face. You will NOT get a load that gives excellent performance in .30-06. Once you get close to 1.5 times the charge weight of the 7.6X39 ammo you are going to have to watch very carefully for pressure signs. Since this powder is too fast for big cases, you're likely to reach maximum pressure levels significantly before commercial .30-06 ammo. And, make damn sure you're wearing good eye protection, leather gloves, and a leather jacket. That should protect you somewhat from the flying metal fragments.
