What would y'all say is the effective kill range for a big tom with a 20 guage? Would most likely be shooting 3" #4s

If you haven't bought your shells yet for the hunt, try Heavier than lead #6 shot. Have seen several turkey taken cleanly at 40+ yards from a factory full choke in a Remington 870 youth.

Patterning that gun and my 2 20ga guns, there is no way a turkey head and neck could escape being busted unless the shooter completely missed at 40 yards.

Good luck this year

With #4s you have less shot in the pattern and one piece of lead #6 shot will break a turkey neck at 40 yards or more. The problem with bigger shot is less shot in the pattern so less likely to hit the vitals.

#6s it is then. So I should be fine with anything under 50 yards?

Taking my girlfriend on her first turkey hunt and I've only killed turkeys with my bow so I'm new to taking them with a shotgun. Just want her to have the best chance possible and want to know what her limitations will be.

Thanks

You can get XXfull turkey chokes also..

A lot of impressive patterns in 20 gauge have been thrown with the right choke and the Federal Heavyweight #7. I like the #7's because of the density of the pattern, yet still maintains the energy needed to break bone. If you want to do some research, check here:

http://oldgobbler.com/Forum/index.php

I would limit shots to 35 yards unless you know exactly how your particular gun patterns.


Gman

A 20 ga can kill a turkey just as far as a 10ga, provided you put a pellet in the right spot. Obviously, pattern density is the variable. Pattern your gun and shoot as far as you have a dense, consistent pattern. My son shot his first two turkeys with a .410, and quite a few after that with a 20. Longest shot with the 20 with factory full choke and 6's was about 35 yds, which is a lot farther than it looks..
Good luck.