smokeless74-
I'll try to be brief:
Be careful duplexing with 2015 and 10x in the .40. They would be best shot as single powder loads.
Also, minor point, 2015 and 10x are not close in burn rate.
With the 2015 load, you could drop the 10 gr of 4759 and still be 3-5 grains over where I would be comfortable (I would be guessing, but I wouldn't doubt this load to be over 3k with only 68 grains of powder
![Eek! :eek: :eek:](https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f631.png)
)
The 10x load you referenced would be better, but again I would drop the 4759 and keep 10x to 60 grains max.
Stick with the 4759/varget combo if you want to duplex. Your buddies speed for that load is spot on. I got 2,731 with that combo. Varget is hard to beat, but you may also try N140 or RL-15. Keep your total charge to 80gr. (I'm @ 76 gr total. 12/64 N110/Varget for 2,900. I have gone past 3,000 fps @ the 80 level safely, but my load is scary accurate and I don't need another 100 fps)
All of the above is just my opinion- do what you want. Just be careful. FWIW, RB built the first .40, SW built the 2nd, and I built the 3rd. All back in 2007/08 if my memory is correct.
OK, not so brief. Sorry.
Good luck-
Judd