I got lucky some time last year and bought a kit CVA Hawken that had a 12 gauge barrel and so I got it to fit onto my .58cal stock with just a few minor adjustments at the tang. Man you talk about fun! I have both an elk gun and a grouse getter!
I didn't draw any big game tags except for in new mexico, so my september will be spend in colorado, grouse hunting with her! I did a video of this shoot, but will have to wait to show it once it uploads.

I used 90gr Pyrodex Select, 1 1/8oz 7 1/2 shot and of course all the fillers and wads. I'll be experimenting with this tomorrow. I am able to shoot out to 50 yards with very good pattern.