The more open your pattern is, the smaller the shot you want to use to increase the density of your pattern, and the more you want to reduce the distance of your shot.

The Magnum Blends are superior shells without a doubt.....
you do need to pattern your gun

I'd recommend win HV #5's at the distances your looking at

I patterned my gun and my lethal range is 30 yards. I emailed clark from allaboutshooting.com and he helped me with critiques on my pattern. Im shooting a moss 500 28" barrel with 3" win long beards #4. They look great. Once i save more money im going to put a red dot on my gun. Then itll be even better

Sounds like your well on your way. What choke you using? Just my opinion but I would think it could easily be a 40 yd gun. Calling them inside 30 is much more exciting anyway. Clark is a great guy. He will go out of his way to help you.
Ray

What Oldtimr said, or borrow a few different brands, loads and pattern them. Even try changing chokes (full, x-full or even modified) and see what combo patterns best in your shotgun. And ALSO HITS WHERE YOU'RE AIMING.
Once you find what combo your shotgun likes the next step is to determine how far that load will pattern for an ethical kill on a mature tom.
I have a little Rem 870 youth model 20 gauge that will, with 3" Winchester Supreme #5 shot, roll a turkey flat at 40 yards. But I like to get them much closer and sometimes I've let them get too close.

Yea my 40 looks decent. I just dont want to risk it at 40. Its fun gettin em real close. And im shootin the factory full choke