Here in KS, the AG sales tax exemption is for anything that is used in the production of crops, farming or ranching, or anything that is consumed--, ie. oil, chemicals, etc.
I think you would be hard pressed to defend it if you were ever audited, nor would I bet that the store would allow it, as it is their butt on the line if THEY ever have a sales tax audit.
I am a hunter ed instructor, and I deduct most of my ammunition, powder, even my gun purchases, as charitable deductions, because I use most everything in classes that I teach.
Just my .02!
Tim