Re: Reloader 7 powder
Use Hodgdon Lil' Gun. Believe it or not, you can get 300-400 ft/sec increase in velocity with Lil' Gun and maintain great accuracy.
Now don't everyone attack me at once for that statement, but in my custom Hart barreled .221 rifle I get an honest 3,600 ft/sec with the 40gr B-Tip (moly) bullet and Lil' Gun powder. This load will shoot .5moa at 200yds regularely.
I'd suggest that you start at about 15.5gr and work up in .1 grain increments. I won't tell you what I use because it is max in MY rifle and may not be a good reference point in any other rifle. I did, however, load beyond the 3,600 ft/sec but quickly saw signs of excess pressure.
You can always use 4198 which has been the traditional powder for the .221 FB.