Shu, if u wanna use your reticle to measure different size tgts. it's very easy to apply the "modified mil-ranging" formula if u have the right tgt. size to stadia subtention relationship. To save time here i'm gonna copy a post we had on 24hourcampfire.com. Take a look at the 2 postings i put on there regarding the system--
This system has a couple advantages over the "subtention change with magnification change" that a lot of guys use IMO.
Good to see your 12" pr. dog is working. FWIW Leupold uses a 7.3" std. for their pr. dog (2.33 MOA @ 300 yds.).