Question on 870 supermag shot pattern

[Mizzouhntr]

So im new here, found this great forum trying to up my turkey hunting game. So my backup gun is a Rem 870 Supermag with a 24 inch barrel, Hevi 662 turkey choke, Longbeard 3.5 #6. So this is my first go with the long beards, and I deep cleaned my barrel as per instructions found here. Deep clean, not polished. So my shots all hit 6 inches high at a stepped off 40 yards. My very first shot on 42 degree day had 219 in a 10 inch circle. Shot number 2 was 190, shot # 3 was 159. Is such a dramatic drop off normal ? Is there anything i should be looking for that could be affecting my pattern, ie shot form, choke tube loose, barrel not tight. I honestly did not check any of those until i got home. I plan on trying again this week, maybe with some #5s, and shooting against my 835 with my new ssx choke which is arriving soon.

Any suggestions

[Longshanks]

Check the nut that keeps the barrel tight, may be backing off. Tighten with large set of pliers and put something like leather around the nut so it won't chew up the metal. If that is not it,  get a tico tool and use between shots. Takes about 5 seconds to clean out the barrel. Adjustable sights will take care of the 6 inches high.

[Mizzouhntr]

Well, the choke tube was not fully tight.. talked to the nephew, who said he started unscrewing it but tightened it back.. seems he barely did. But that wasnt until shot #4. Also... i actually measured with a 9inch dinner plate.. went back and put 1/2 in all around. So numbers were better.. 256, 224, 207, 183.. so im not in panic mode as much anymore.. that will teach me to fully inspect my gear.. however, there was a serious decline from 256 to 207 in just 3 shots... still seems excessive

[Mizzouhntr]

May just be my gun only likes a clean barrel? Just like this guy

http://oldgobbler.com/Forum/index.php/topic,53160.0.html