Kid;
Have never done this so just a few thoughts. First 440 grains is very near to 1oz, 1 1/16 oz = 465 grains. 2 3/4 drams = 75 grains. for this usage I would personally think the 3FG would likely give the better results. I do recall an article from an older American Rifleman (pre plastic wadding etc) where some extensive tests on slug accuracy were carried out (smokeless powder) & they recommended a minimum of .200" of card wad directly beneath the slug to prevent filler wadding from being forced into the cavity of the hollow base. No data of course to back it up, but I would think the 2 3/4 drams with that wt slug should easily reach your 1000 fps & still be a fairly comfortable load to fire. Have fun with your project & do fill us in on your results.
