Port arms (gun held in front of your body, muzzle angled up) is the safest way to carry as you approach a dog but it’s not the best position for bringing a shotgun into action. Going straight from port arms to shouldering the gun creates a lot of movement, puts the distracting barrel in your face, and it makes you bring the muzzle down when it should be moving up to mirror the bird’s flight path.
Fortunately, you’ve got lots of time to mount the gun when a bird flushes at close range. It may not seem like it, in the excitement of the moment, but you do.
Here’s a drill you can do to learn a kind of two-step gun mount, first, with an unloaded gun, then with loaded gun and a trap throwing going-away targets at your feet.
Start with the gun at port arms. Imagine the bird flushes. The first move is to bring the muzzle down to just above horizontal to a ready position and pointing in the direction of the bird. The toe (bottom of the buttstock) is now almost touching the top of your hipbone.
The second move is to bring the gun up to your face as you mount it, pushing the muzzle out toward the bird.
Do this with an unloaded gun at home. Try a few shots standing still, then pretend you’re walking in on a bird. Once you’ve got the move down, go to the field and walk toward a trap, either a manual trap or, with the range owner’s permission, a trap on a trap field.
Have a friend pull the bird first on your call, then pull randomly to take you by surprise and catch you mid-step.