JRH said:
Suggestions on how to improve for turkey hunting appreciated.
You didn't mention the yardage...but I personally wouldn't take a shot at a turkey with that pattern at whatever that yardage is. In terms of suggestions, you have got to use a larger shot charge.
7/8oz #4s won't get it done reliably unless you're going to hold your fire until you get one close, 10-12yds.
One of the few old sayings that actually seem to have merit from "the old days" is this:
"Little powder, more lead, shoots far, kills dead"
Meaning, to use a powder measure to measure both powder and shot...and in a ratio of more shot to powder.
(this all assumes good quality firearms in well maintained good condition, etc, of course)
One example of a proven .20ga muzzleloader turkey load good for 25yds is:
70 grain powder measure of 3F (or 80grn measure of 2F)
1/4" to 1/2" amount of OP wad(s)
120grn powder measure of #5s (1+5.8oz) or 6s
1 (or 2) OS cards
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Here are results from 60grns powder & 100grns of lead at 25yds with a small 3.5" tuna cans, shot with a .54cal/.28ga cylinder bore.