I have been working on setting up my 870 Express 20 gauge for some local 3 Gun. Yes I know it's a 870 and a 20, but it's the only shotgun I have right now.

Today I was shooting the two loads I can find locally, both 3/4 oz Foster slugs, 1600 fps. I just have the vent rib and bead sight, but holy moley does this thing shoot low. I had to hold the bead a head height over the full size silhouette to punch 3 holes in the bottom of the paper at 100 yard, the same hold at 50 yards got hits in the lower 1/3rd of the paper. This surprised me, every other bead/rib shotgun I've owned has always been an even hold at this distance, and usually within 6".

Anyone have any ideas? Would one of those sights that clamp on to the rib fix it?

There's enough going on in a match without having to do extreme holds, or pointing the shotgun at the top of the berm.

Thanks!

Is your barrel choked?  If so, have you tried a different choke tube?  Happen to have a spare barrel you could try?

Unfortunately unless you are planning on bending the barrel (not recommended!), your option would be to put some sort of rear sight device in place that forces you to raise the muzzle to get the front bead in the rear notch.  

I can tell you that my Win SuperX 3 reacts quite differently to different slugs.  The ones my shotgun likes best are Federal Low Recoil slugs, and I've bought them every time I find them at Gander Mt or Bass Pro.  Even then my shotgun will print about 5" left at 100 yards.

I shot primarily with a improved cylinder, years of testing in other s/g's I've owned usually are most accurate with IC. I did shoot a couple through a cylinder, no difference. There are only 2 commonly available slug loads in my area, otherwise I have to roll my own.

Finally had time to do a little more research today. The barrel clamp may be causing it, there is an interesting 8 yr old thread on the Brian Enos forum where that caused some major POI shift.

I may try one of those clamp on sights, but for sure when the range thaws out I will play with the positioning of the clamp and see what happens.

Update

Took the clamp off, same thing. Moved the clamp around. Same thing. Forgot to bring my PAST recoil pad (shooting slugs off the bench in a light pump starts hurting around slug no. 20), I give up. I read a few threads online about the bending the barrel apparently some of the guys shooting trap guns that cost more than my new car did do that...count me out. I have this image in my mind of Bob Hope in one of his "Road to fill-in-the-blank" movies with a rifle that is bent to an absurd angle.

I learned in my messing around with sports cars there usually are some very good reasons everyone gravitates toward certain stuff. A running joke on a motorsports forum I am a member of is the answer to every single question is "Miata". After buying one I kind of agree. So in 3 Gun the answer to "shotgun" is a member of the Benelli family: M2/Franchi Affinity/Stoeger M3000-M3K.

So I have put the Remington up for sale, when it sells the proceeds will go to my dealer to start paying off a Stoeger M3K.