The best shotgun shell for shooting ducks is a 3 to 3 1/2 inch 12 gauge with number 2 shot.
It will depend on what you are hunting and which brand of shell your shotgun patterns best.
Modified.
shoot it with a sawn off shotgun
It all depends no what you are shooting. You can find many websites that discuss chokes and the applications of which is best for what type of shooting you are doing.
Usually modified, but each shotgun may be a bit different.
It is very recreational and great activity where participants using shotgun shooting chokes. It is one of the three major disciplines of clay pigeon shooting, sporting clays and trap shooting. There are many types of skeet which include Olympic skeet or international skeet. It is designed to be a 30-inch circle at 21 yards distance.
federal law is three rounds when hunting migratory birds (Ducks, Geese,Doves.) the magazine limits will vary from state to state as to how many rounds can be in the gun when it is used for hunting/shooting Best to call the state game and fish commission in the location state
A full choke is the best for waterfowl.It will keep your pattern tight as long as possible due to the distance involved with shooting ducks and geese in flight.
Either a full choke,or extra full choke shotgun barrel.
either a heavy 6 or any turkey load if your close i would use #2 if your shooting farther
The only way to know is to pattern your shotgun with as many different kinds of CORRECT ammunition as you can afford. Firearms will often show a marked preference for a brand or weight of shot.
I would use any shell except steel shot shells in your 1961 vintage browning shotgun.I would check to see if your chamber is for 2 3/4in shells,or for 3in.shells.Other than that I would use whatever shell fits the game that you expect to hunt.