A friend of mine has purchased 2 new uppers for his AR, one in 221 Fireball and the other in 300 whisper.
He has asked me to help learn how to handload for them. To this end (before speaking to me) he purchased a Dillon reloading system(more on that later).
I've been a handloader for about 10 years,and consider myself pretty good at it. All of my experience is loading for my military bolts guns on a rockchucker. I have no experience with a progressive press, and the only semi auto I've loaded for is my CETME.
I'm hoping those of you who have experience with the Fireball and the Whisper will share your knowledge with me. I've read thru the archives and picked up some tips for semi auto's, and hope you folks can add even more.
As for the Dillon, well, I guess I'm in for some new learning as well.

I have relaoded the 300-221Fireball(aka 300 Whisper) for a number of years and countless rounds.
What exactly are you searching for-subsonic? something in the 2500 fps range w/ a lighter weight bullet?

Re-post w/ specifics.Happy to add what I know.

Gary

Google "300 Whisper load data" and you'll have tons of info, there's a forum just for that cartridge. One tip, if you run across 221 Fireball brass, get all you can get, we just received an order of new brass that was ordered 8 months ago. Just curious, where did he get a 221 Fireball upper?

Sometime this week. I haven't seen it yet.

Who Made His barrels?

Here is some good info on the Whisper. It was given to me by an AR member.

http://quarterbore.com/300whisper/subsonic.html