I would agree on the rim-fire being better just for sake of price at 25 meters. With about nine AS under my belt, I have used a .22 LR at 8 of them. My first appleseed i used a mini-14, and spent a ton on ammo. Ever since i've used my ruger 10-22. HOWEVER! At the last one, I decided to do a reality check. I asked myself the question, "which gun am I defending myself with and should be able to use proficiently?" Well, as obvious, a semi-auto was a gimme, and my AR-15 was choice numero uno. Therefore, I practiced with it until I got rifleman. (P.S., this only took one page of sighter squares and one AQT to getta 225.) Anyhow, it is good to know that you are proficiant with your battle rifle,

not just your chipmunk killer.

So just to put things into reality, I would extremely recommend using both.