BTW...Your choke is measured in micrometers...my 1st list (above) is showing fractions of an inch.
Meaning your .670 choke is an
Improved Modified...remembering that it screws
into your barrel and then further constricts down to .635 = .025 = IM
And at the yardage you describe testing on the pallet ( 20 yds )...damn right it's gonna be a tight group...( but good luck getting a yote in that close !! )
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Here's a list that breaks that down:
Micrometers..................
Inches..................
American Name
0.................................... .000......................... Cylinder
127................................ .005......................... Skeet
254................................ .010......................... Improved Cylinder
381..................................015......................... Light Modified
508................................ .020......................... Modified
635................................ .025......................... Improved Modified
762................................ .030......................... Light Full
889................................ .035..........................Full
1143.............................. .045......................... Extra Full
1270.............................. .055......................... Super Full
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Hope I made that clear...