Ya had a great day shoppin...turkey gear.....AND PRIMERS....WOW !! I never could operate one of those diaphram thingy-bobs. Guess it relates to not being abe to whistle very well either.... I just stick to my ole Box call...Had it for about 25 years. To locate a gobbler a Crow or Owl call is good. Toms like to answer them. Finding the right choke and shells for a turkey gun is like huntin for a proper reload for a particular rifle. Me and my oldest grandson both shoot a 835 Mossey....Different choke and shells for the best pattern. You will find the smaller shot ( #6 i.e.) will hold a tighter pattern than larger shot (more pellets also). Now that is a general rule.....Hope your mixture is satisfactory..... How do you measure your patterns .......For Turkey I like a 30" at 30 yards with 60%+ of the pellets in that diameater. I would think with the 870 and 3" 12 ga. you would be good to about 50 yards. REMEMBER....Head and High Neck shots....Only takes 1 pellet up-side the brain housing group.