I don't know how a 300 win mag will feel.

However, I put one on my 12 ga. Benelli Nova 3 1/2". And shooting 00Buck feels about like a 30-30 with 170 gr loads. It is definitely worth the $.

I would think that 12 ga. 3 1/2" buck will kick as hard as a 300 Winny, so it too would probably feel close to a 30-30, which isn't bad at all.