Even if you silence it you will still have the crack of the bullet breaking the sound barrier. It would be quieter than a normal rifle, but still noisy. The big difference being it is very hard to locate the sound like you would with a normal rifle report. Plus they are a pain to get, if you can get one, expensive and may not even be legal to hunt with. You have to get a permit to own one I think.

Keep in mind short barrels tend to make more noise. As would anything with a ported barrel, so stay away from that.

I would suggest a .223 with a varmint bullet that is very frangible in something you can shoot well for a second shot. A semi auto would be nice if you could afford it, but not needed. This would easily cover the range you want, works just fine on that size game and smaller, inexpensive to shoot, shouldn't be overly loud and would reduce ricochets with the right bullets.

My opinions and nothing more.

Paul