If you are looking for a pump gun for your son - do not turn down a good deal on a 12 gauge - many loads available will have similar or less recoil than some 20 gauge rounds. Back in the day, I had a Remington Wingmaster in 20 gauge, that was built on a 12 gauge frame. Weight, balance and fit of the gun likely makes a difference in what he wants to carry. If money is no issue, maybe consider a 28 gauge - guns probably similar cost, but ammo typically a LOT more expensive than promo 12 gauge. It partially depends on the game being hunted - most of Canada still allows lead shot for upland game birds - like grouse - so a 3/4 ounce 28 gauge is completely adequate for that, but I think most of Canada requires "non-toxic" shot for migratory birds - many folks use steel - by far the cheapest, although other materials available - like Bismuth, or Tungsten or alloys of those - so 12 gauge or even 10 gauge get the nod for waterfowl. My very first "decent" pump shotgun was a 12 gauge Browning Pump Shotgun - fixed modified choke, 26" barrel - our son has that one now. There is a 12, 20 and 28 BPS in the cabinet here, now, as well as a 12 gauge Winchester Model 12 and a Browning Synergy Euro Field in 28 gauge.