[CSBadKarma]

I'm in the middle of building my 870 Trap only shotgun.

Did anyone see a need for more barrel weight to improve the swing?
I was wondering about using a 12ga hull with the primer sealed with epoxy and filled with shot and placed in the far end of the magazine. What would a shot filled hull weigh?

This presents another question: Where should the right balance point be located?

 

[DevilsAdvocate]

I believe some extra weight on an 870 would make a better trap gun.
I have weighted mine and find it swings better for me. I have used
two different ways to add forward weight. I like the Tom Morton
Poor man recoil reducer, and I have also made up weights that
I can add to the magazine cap. The added weight, of course, also
helps with recoil. This is something you just have to experiment
with and find what you prefer. The shell filled with lead will work
quite similar to the Morton recoil reducer. You should be able
to add about 3 ounces by my estimate. You can do better than
this, with the Morton reducer, and it is is also cheap and easy.