Improved Modified Choke Patterning

[cz74]

I am using Federal 12 gauge 2-3/4" 1-1/8 oz 7 shot using my SKB 720 Field O/U with 28-inch barrel. Top barrel has #3 Imp Modified choke, bottom barrel #4 Modified choke. Patterning at 17 yards. Aim the front bead at center of target, Imp Modified choke patterning consistently at upper half of where I was aiming. Bottom barrel with the Modified choke patterns the equally, half the pellets hit above center, half below center. What's going on here? Any thoughts?

[Thefeeder]

Switch the choke tubes and see if you get the same result. It can be the choke tubes are off or the barrels are not well regulated. 17 yards is very short...pattern at 30-35, it may or may not be a big issue

[Ducky's Dad]

#7 sounds like steel shot. Steel does not behave like lead and patterns much more tightly. If you are patterning that stuff as a hunting load, try it at 30-40 yards as suggested. Point of Impact is not the same as patterning. Lots of shotguns are intended to shoot high at normal ranges to deal with rising targets (pheasant, quail, chukar, etc.). Might be the way the gun was designed.

[BOBGBA]

Switch the choke tubes and see if you get the same result. It can be the choke tubes are off or the barrels are not well regulated...

I'm curious to see how this turns out.

#7 sounds like steel shot. Steel does not behave like lead and patterns much more tightly. If you are patterning that stuff as a hunting load, try it at 30-40 yards as suggested. Point of Impact is not the same as patterning. Lots of shotguns are intended to shoot high at normal ranges to deal with rising targets (pheasant, quail, chukar, etc.). Might be the way the gun was designed.

My bet is that the use of steel though any of SKB's choke tubes tighter than modified is not recommended.
I couldn't find a manual for the 720 online, but I put this together from the SKB website.

SKB Choke Tubes Steel.jpg

OP - Are you using steel? Is there anything in the owners manual?

I just called SKB (800.752.2767) and they said no steel shot in any choke tube tighter than modified.
He said they'll have the website guy take a look at the website when he gets back from vacation.

[cz74]

Looking back at my notes from that range day, just realized I was using the Winchester SuperX 12 gauge 3-inch 1-1/8 oz. #4 shot, so yes Steel shot. My SKB manual confirms: "Steel shot pellet size #2 and smaller should not be fired through your shotgun with a choke tighter than Modified" Thanks everyone!

[BOBGBA]

...My SKB manual confirms: "Steel shot pellet size #2 and smaller should not be fired through your shotgun with a choke tighter than Modified" Thanks everyone!

Are you sure that it doesn't say: ..."Steel shot pellet size #2 and smaller larger should not be fired through your shotgun with a choke tighter than Modified."...?

Maybe it's a Turkish to English translation problem.

It's the larger steel pellets that cause the problems.

This is what Carlson's say's about one of their chokes:
The Close and Mid Range chokes can be used with all sizes and speeds of steel, lead, or Hevi-Shot.
The Long Range is NOT to be used with any STEEL shot larger than BB, or with any STEEL shot faster than 1550 FPS

[Ducky's Dad]

Huge difference between 2-3/4" #7 and 3" #4! 7s should be OK thru a steel-rated IM choke. I can tell you that I used to (long ago) hunt snow geese with an old Citori using 3" #2 steel and an IM choke in one barrel. Killed geese just fine, but those pellets hammered the choke threads into the barrel and I had to pay a gunsmith to get the tube out. Destroyed the tube but saved the barrel. Be careful out there.

[JagerDog]

Switch the choke tubes and see if you get the same result. It can be the choke tubes are off or the barrels are not well regulated. 17 yards is very short...pattern at 30-35, it may or may not be a big issue

What he said.

Barrel regulation is distance dependent.

Choke tubes can be a bit eccentric.

Every shotgun has a bit of it's own personality.

[FourT6and2]

Are you sure that it doesn't say: ..."Steel shot pellet size #2 and smaller larger should not be fired through your shotgun with a choke tighter than Modified."...?

Maybe it's a Turkish to English translation problem.

It's the larger steel pellets that cause the problems.

This is what Carlson's say's about one of their chokes:
The Close and Mid Range chokes can be used with all sizes and speeds of steel, lead, or Hevi-Shot.
The Long Range is NOT to be used with any STEEL shot larger than BB, or with any STEEL shot faster than 1550 FPS

Smaller, as in smaller number. Smaller number = larger shot.