Check w/ county conservation officer/game warden. Find cafe farmers/ranchers go to every morning and let these folks know you
want to shoot prairie dogs and you will probably get an invite.
Converted my .22 Hornet to .17 Hornady Hornet and had a similar problem while reforming my .22 Hornet brass
except my reformed brass separated just above the web. I eventually gave up and threw it all away.
There was an article in the July, 2010, copy of Shooting Times by Allan Jones on
how to deal with this problem. Supposedly only works with new brass. If interested
let me know and I'll send you a copy. Essentially what Allan suggests is that
you expand the mouth of a 7mm RM with say an 8mm...