I was pattering my 1187 today and the pattern except it was about 6" left. "Holding" right fixed the issue but I know that is not the right answer. Any suggestions? I have not swapped the choke (.680) yet as I bought only one.... Has anybody experienced this?

Does it just have a front bead? If that's the case you might see about putting some fiber optic adjustable sights on it.

Yes it has a front bead...

Were you shooting in a stiff right-to-left cross-wind? Wind will move your pattern, especially at longer ranges.

I was shooting at 35 yards using Federal Premium #5 Heavyweight ...

I own 2 Mossberg 835's and had the exact same issue with 1 of them. 2 guns with the same chokes and same shells shot 2 totally different patterns from the same distances. Only way I was able to fix it was with a red dot sscope. I hate to say it but its probably going to be your only fix as well or at least a set of open sights with an adjustable rear sight. Good luck and dont be discouraged because at least you have some options. Good luck.

Go get yourself a set of Tru Glo Fiber Optics sights. Make sure they are the clamp on and not magnetic. Measure the width of your rib and they do make a set of clamp ons as I had them on my 11-87.
Also make sure they allow for Windage and Elevation ~ means you can move the back sight up and down or left and right.

The front sight fits right in front of your current shotgun bead - so there is no reason to take it off.

Patterning
I start patterning using trap loads. I use a cheap box as the recoil is less, the cost of shooting quite a bit is less as all I am trying to do is dial in my sights so I can punch out a quarter sized (25 cent piece) dot out of my cardboard at 10 yards. That is where I start.
When that dot is completely gone I move back to 20 yards to check my pattern. Still good? Great.
Now I switch to the second target on this link.
Link
http://lewand.tripod.com/turkeytargets.html

Now I will adjust my sights or my scope - both are really the same so I can consistently put the bottom center of my circular pattern at the point where the skin starts and the feathers stop on a turkeys head. Why? It is one consistent aim point that all turkeys have andis very easy to see.


The Picture I made is crude but what I am after is completely encircling the head with my shot cone. Once I am happy doing this with my trap loads I do switch to my Turkey Loads. I have found that I needed no further adjustments to my sight I chose at all.
I then shoot at 30, 40, and 50. My rule is 8 to 10 hits within the bones of the neck, skull or eye. All those are clean kill shots. Any less than that and I have developed my maximum range.
Not only do yo save ammo cost - you save yoru shoulder too.
One last thing - I do use a bench to develop the pattern - then go to my sitting position to use my turkey loads.

Hope that makes sense - Be Safe and Good Luck out there!

Dave......JW

might try a center bead, maybe an adj. to the butt stock, try a cheek pad, bet it is you, not the gun, use a good rest. chokes can in fact be made to change the direction of the shot but bet that is not the case here.

cheers

Probably not the answer you want to hear, but I can tell you I had problems with my gun when using "extra full" or "turkey" chokes. They would not shoot accurately based on my front bead placement. Mostly mine shot several inches high. I've since only used the factory chokes and use the "full" for turkey....now all is well.

Thanks for all of the input. There is a chance I am "bucking" the gun right when I pull the trigger. I am going to get a set of adjustable sights just to make sure. Like I said the pattern was consistent along with consistent shot placement.