Question for .172 barrel owners

Nation, 

I have, in my arsenal, a .172/.176 bull barrel that I will one day put on an airgun. 

My question is, what size ammunition/slug/pellet are you guys using? Do you use "regular " reloading dies to create what you need? I would like to investigate this for a future project down the road. I would like to hear about your successes, as well as failures, so I have a point to start.

Thanks,

Tom Holland 

Field Target Tech 

Fieldtargettech.com